2014 Biology Notes
Transcript of 2014 Biology Notes
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 1/74
BIOLOGY MASTER NOTES [PRELIM + HSC] SUMMARY
CHAPTER 1: A LOCAL ECOSYSTEM
1.1 TERRESTRIAL AND AQUATIC ENVIRONMENTS
• An ecosystem is any environment containing living organisms interactingwith each other and with the non-living parts of that environment. It can be
any size or any area.
• Environments have abiotic and biotic factors, or non-living, and living factors.
• The habitat of an organism is where it lives.
• A group of organisms found living in together in one place is called a
community.
• Ecology is the study of the relationships living things have with each other
and their environment.
• Terrestrial environments are environments on land; auatic environments are
environments in water, salt or fresh.
ABIOTIC CHARACTERISTICS INCLUDE:
• Viscosi! ! a measure of how hard it is to move through a gas or liuid.
"ater has high viscosity, ma#ing it harder to move through. Air has low
viscosity, ma#ing it easier to move through.
• B"o!#$c! ! the amount of support e$perienced by an ob%ect immersed in
liuid or gas. "ater provides support to both animals and plants, helping
them maintain their shape and functions. Air does not provide buoyancy, and
organisms must support themselves.
• T%&'%(#"(% V#(i#io$ ! "ater heats up slower than air, this temperature
and the ability to avoid or tolerate heat loss is important to organisms.
• P(%ss"(% V#(i#io$ ! The earth&s gravitational 'eld gives rise to di(erent
pressures in air and water. )ressure increases rapidly in water due to depth.
*n land pressure +uctuates, sometimes a(ecting breathing and +ight of
animals
• A)#i*#i*i! o, -#s%s ! * and * are important for living organisms. In
water, gas availability is low, depending on temp. i(usion is slower and
more gases can be dissolved at lower temps. *$ygen availability a(ects
distribution of organisms and their body structure.
• Io$ #)#i*#i*i! ! Ion/ An atom or molecule with a net electric charge due to
the loss or gain of one or more electrons. *rganisms need to be able to copewith osmotic di(erences in their cells and the environment. 0altwater
environments contain 1.23 sodium and chloride ions, whereas freshwater has
low ion concentration. Ions are available in soils depending on composition,
in+uencing type and plant growth.
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 2/74
• Li- #)#i*#i*i! ! Auatic may be re+ected scattered or absorbed,
decreasing rapidly in depth a(ecting organism distribution. Terrestrial light
passes easily through air, plenty of light available.
POPULATION
• Dis(i"io$ ! "7E4E a species is found
• A"$/#$c% ! 7*" 8A9: of the species live in an ecosystem
• Dis(i"io$ and abundance are both a(ected by biotic and Abiotic factors
• To measure distribution, we can s#etch the area, or more commonly use a
transect, recording organisms found across the 'eld in line with a narrow strip
of area.
• To measure abundance, we can count all of a species in an area, or through
the use of two methods/ 4andom uadrat, and capture recapture.
• R#/o& Q"#/(# ! sed to record abundance of plants and slow-moving
organisms such as medulla and periwin#les. It involves placing a uadrat
suare randomly in the chosen area, and recording how many organisms arefound in that uadrat. This is repeated many times and the total number of
organisms found in the combined uadrats is compared to the size of the
study area to determine the abundance.
• C#'"(% R%-C#'"(% ! sed when species studied is constantly moving. It
involves capturing and tagging, or mar#ing, a sample of animals, say 2, and
then releasing then. Then return bac# to the same site later on and
<recapture= a sample, say >?, a count how many previously tagged animals
are in the new sample. Abundance is calculated through the euation/
A"$/#$c% 0 $"&%( c#'"(%/ $"&%( (%c#'"(%/2$"&%( &#(3%/
i$ (%c#'"(%/
PHOTOSYNTHESIS AND RESPIRATION
)hotosynthesis is the process by which plant cells capture sun energy and
combine it with * and 7* to ma#e sugars and o$ygen.
4espiration is the process by which cells obtain energy through the brea#ing
down of organic molecules, particularly sugars to produce * and 7*,
releasing energy.
These processes are related because energy from the sun is incorporated into
the products of photosynthesis, used by plants. "hen these plants are
consumed, the organism obtains nutrients used in respiration so that they toocan obtain energy. This energy drives the metabolic processes in an animal
and ultimately drives ecosystems
PS 4 THE EQUATION 0 CO5 + 6ATERLIGHT +
CHLOROPHYLLSUGAR + O7YGEN
CR 0 GLUCOSE + O7YGEN 8 CO5 + 6ATER + ENERGY
AEROBIC CELLULAR RESPIRATION
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 3/74
Involved a series of chemical reactions, releasing small amounts of energy
into the bond of organic molecules, such as sugar. This energy is then
released when the bonds are bro#en, which is then transferred to AT).
8ost AT) originates from the cellular organelle, 8itochondrion.
• Energy from respiration is used inside the organism, such as heat, growth,
and repair.
1.5 LOCAL ECOSYSTEMS: INTERACTIONS AND RESPONSES
RELATIONSHIPS BET6EEN ORGANISMS IN THE SAME ECOSYSTEM
• The relationships between organisms in an ecosystem can be comple$,
however they usually adhere to one of the following common relationships/
• P(%/#io$ ! A feeding relationship where one animal, the predator, #ills and
eats another animal, its prey. Also #nown as a predator-prey relationship it
can vastly e(ect population numbers in an ecosystem, with rises and falls of
predators usually following rises and falls of prey.
• A**%*o'#! ! The production of chemicals by a plant that can have good or
bad e(ects on the plants surrounding it, in+uencing growth and development
of neighboring plants for good, i.e. repelling parasites and predators, or bad,
i.e. poisoning or hindering the other plants.
• P#(#siis& ! "here one organism obtains food from another, harming the
host in some way but not always #illing it. 8ost free living organisms have
parasites.
• Co&&%$s#*is& ! "here one species bene'ts o( another, but does not harm
it. 0uch as the remora and the shar#.• M""#*is& ! @oth species bene't from each other, such as the ringtail
possum and the bottlebrush tree. 4ingtail gets food, whilst it&s dropping
encourage growth of the tree.
BIOMASS AND ENERGY PYRAMIDS
@iomass is the amount of living material in an organism or group of
organisms at one time.
@ecause plants are producers, their biomass is the greatest in the chain, with
it slowly decreasing as it moves through the trophic levels.
5or this reason, herbivores generally have a greater biomass than carnivores.
0imilarly to @iomass, E9E4: is also lost as it moves up the trophic levels.
This loss is shown by an energy pyramid, which loo#s very similar to a
biomass pyramid as energy is transferred in food that ma#es up the biomass.
The further along in the food chain the organism is, the less energy is
available to it.
• Energy is lost in a number of ways, usually though heat, growth, and as feces
or urine.
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 4/74
ADAPTATIONS
An adaptation is a feature of an organism that ma#es it well suited to its
environment and lifestyle, it can be structural, physiological, or behavioral.
Adaptations help an organism to survive and reproduce in its ecosystem
•
They are inherited characteristics, a result of natural selection.
CHAPTER 5: PATTERNS IN NATURE
5.1 ORGANISMS: CELLS AND THEIR STRUCTURE
THE CELL THEORY
• All life forms are made up of units called cells, the building bloc#s of which all
living organisms are made.
• The cell theory states that/ ells are the smallest units of life, All living things
are made up of cells, and all cells come from pre-e$isting cells.
HISTORICAL DEVELOPMENT
• The development of the cell theory went hand in hand with technological
advances, particularly of lenses and magni'cation devices, such as
microscopes, in the >Bth century, enabling much greater detail to be seen.
• The 'rst recorded study of cells was in the >Cth century by 4obert 7oo#e, who
used his home-made microscope to view a thin piece of cor#, and identi'ed
the nucleus as a large body found inside cells.
•
*ther notable scientists who helped develop the cell theory areDeeuwenhoe#, who described unicellular organisms from rainwater as
animalcules& and discovered bacteria in his saliva. And 4obert @rown, who
noted how cells have a common structure inside the cell, he named it the
nucleus.
TECHNOLOGICAL ADVANCES
• The light microscope, used e$clusively until >B11, allowed cells to be visible
to some degree, aided by the use of staining to able us to see some parts of
the cell, such as the nucleus, the cell wall, and due to absorption of stain, the
chromosomes.• In >B11, Ernst 4us#a built the 'rst electron microscope, enabling more
detailed observations of all structures to be made.
• "hilst electron microscopes allow much more detail to be shown, they are
e$pensive, ta#e time to prepare, and can only view non living sections.
THE STRUCTURE O9 CELLS
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 5/74
Although ells show great variation, they have certain structures in common
All cells have a clearly de'ned shape or boundary, maintained by a cell
membrane, which encloses the internal contents of a cell.
Inside, cells contain a number of organelles, which each have a particular %ob
to do for the cell.
• ells visible with a light microscope include/ the nucleus, the cell membrane,cytoplasm, cell wall, chloroplasts, and the vacuoles.
CELL STRUCTURES AND THEIR 9UNCTION VISIBLE 6ITH A LIGHT
MICROSCOPE:
N"c*%"s ! ontains the chromosomes, which controls the development and
function of the cell. "ithout the nucleus, the cell will die.
C%** &%&(#$% ! 5orms the boundary between the cytoplasm and outside
environment, controls entry and e$it Fdi(usionGosmosisH of substances to and
from the cell
C!o'*#s& ! ontains many organelles and is where most cell activities arecarried out
C%** #** ! ives protection, support and shape. 5ound in all plant cells.
C*o(o'*#ss ! ontains chlorophyll and are the site of photosynthesis in
plants
• V#c"o*% ! 0tore water and other substances, large and important in plant
cells.
• nder an electron microscope, these features are available in higher detail,
and other organelles can be seen. These include the mitochondrion, the
ribosome, and the olgi body.
6HAT THESE ORGANELLES DO 9OR A CELL
• Mioco$/(io$ ! omposed of folded layers of membrane, it&s involved in
the energy transformations in cells
• Rioso&% ! 0ites of production of proteins in a cell
• Go*-i Bo/! ! A stac# of +at membrane where 'nal synthesis and pac#aging
of protein occurs before secretion
CELL STRUCTURES IN DETAIL
N"c*%"s ! 0pherical and large compared to other cell structures. ontrols the
activities of the cell by dictating which proteins are made. ontains the mostgenetic material in the cell, containing chromosomes, which in turn contain
genes, the inherited information that determines whether proteins are made
or not. The nucleolus, in the nucleus on non-dividing cells, is where genes for
49A are found.
Mioco$/(i# ! sually ?.2 micrometres wide and C micrometers long. They
are surrounded by a double membrane, with the inner being greatly folded,
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 6/74
greatly increasing the surface area for the chemical reactions of respiration to
occur.
L!soso&%s ! 0mall membrane-bound organelles common in animal cells but
rare in plants. They are very acidic, containing digestive enzymes to brea#
down or digest old or damaged organelles.
E$/o'*#s&ic R%ic"*"& ! A system of membranous sacs and tubulesconnected to the nuclear envelope. It provides an internal surface for many
chemical reactions in the cell, and a series of channels through which
material can be circulated. 4ough End. 4et. has tiny ribosomes attached
where proteins are made an transported to the olgi body in transport
vesicles. 0mooth has no ribosomes and is the site for lipid manufacture.
Rioso&%s ! Tiny bodies made up of 49A and protein which may be
attached to endoplasmic reticulum or lie freely in the cytoplasm. They are the
site of protein manufacture
Go*-i o/! ! 0tac#s of +attened membrane sacs, which chemically modi'es
and stores and distributes substances made by the endoplasmic reticulum.
These are received in transport vesicles and repac#aged, ready for secretion
either into or out of the cell.
• C*o(o'*#ss ! *nly found in plant cells, they are surrounded by a double
membrane and contain a comple$ system of lamellae. )hotosynthetic
lamellae also called thyla#oids occur in stac#s called grana, which contain the
chlorophyll pigments needed for photosynthesis.
5.5 S;IPPED: THE SUBSTANCES IN CELLS
THE MOVEMENT O9 MOLECULES
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 7/74
The +uid mosaic model shows how a cell can be selectively permeable and
how di(usion and osmosis can occur.
• i(usion is one way cells ta#e in materials from the environment, and a way
of ridding unwanted materials, such as waste. i(usion will occur when two
areas have a di(erent concentration of a substance, moving until euality is
reached. 9ot all substances can move through cell membranes due to size.
"ater, *, and * and other small ions and molecules can move freely.
•*smosis is li#e di(usion, but only applies to water. "ater will move from ahigh concentration to a low concentration. This is how water leaves and
enters cells.
SUR9ACE AREA TO VOLUME RATIO
A new cell beginning to grow receives nutrients through its surface
membrane
The area of this surface a(ects the rate at which nutrients can enter the cell,
as well as the rate at which wastes can leave
As the cell grows, its needs are greater, however due to the 0urface Area to
olume 4atio, its e$change of material falls
0o as the cells increases in size, its surface are to volume ratio gets smaller,
meaning it can ta#e in less nutrients and e$pel less wastes
@ecause of this, cells can only grow to a certain size, otherwise it would be
unable to survive
5.< OBTAINING NUTRIENTS
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 8/74
CELLS AND SYSTEMS
• In multi cellular organisms, di(erent cells may have di(erent functions, each
wor#ing together for the organism as a whole.
roups of cells similar in function are called tissues, and groups of tissues
ma#e up organs, which in turn ma#e up the systems within the body. Eg.igestive system in humans.
• There is no such thing as a typical cell, however they can be generally
identi'ed as autotrophic, meaning self-feeding& FplantsH, and heterotrophic,
meaning feeding on something di(erent& FanimalsH
PHOTOSYNTHESIS
• )hotosynthesis can only occur if plant cells can obtain *, 7*, and light
from its environment.
• All living things depend on this process as if provides chemical energy for
each living thing.• "ithout photosynthesis, there would be no energy to sustain life.
THE EQUATION 0 CO5 + 6ATER LIGHT + CHLOROPHYLLSUGAR +
O7YGEN
0unlight is absorbed by chlorophyll pigments in the chloroplasts of green
plant cells, and is turned into usable, chemical energy.
0ugar products from photosynthesis are converted to starch and stored in the
cells, causing a green leaf to turn blueGblac# when e$posed to iodine solution
Fstarch testH
• These sugars are also used in respiration in the plant, being converted bac#
into sugars at night and transported by the phloem to the rest of the plant.
nused sugars may also be built up into proteins for growth, of be stored asstarch or lipid.
OBTAINING NUTRIENTS = PLANTS
6ATER AND MINERALS
• )lants use specialised structures to obtain the materials reuired for
photosynthesis from their environment.
• nless it is an auatic plant, most water and minerals are obtained though
root systems with a large surface area, which also act as an anchor
• There are two main types of roots; tap roots; and 'brous roots.• The roots growing point is protected by a root cap, and %ust behind this point
is the region of root hairs, which provide a larger surface area where most
absorption of water and mineral ions ta#es place
OBTAINING SUNLIGHT AND CO5
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 9/74
• The specialised structure for obtaining light and * in most plants is the
leaf, which is where most photosynthesis occurs
• Arrangement of leaves, shape, and size are all factors and adaptations leaves
have to ensure they receive the most sunlight and *, usually being
arranged in a way to receive the most sunlight, and broad and +at to increase
surface area.• The plant has a number of internal structures, each related, and important to
the process of photosynthesis
INTERNAL STRUCTURES O9 A LEA9
• C"ic*% ! A wa$y substance on the surface of the leaf which maintains shape,
provides protection, and reduces water loss due to evaporation.
• E'i/%(&is ! )rotective layer of cells on the upper and lower surfaces,
transparent so can be easily penetrated by sunlight to the photosynthetic
cells within
• So&#%s ! )ores in the leaf that can open and close to e$change gasesbetween the leaf and the environment. This process allows water to
evaporate, which is why they close.
• P#*is#/% M%so'!** ! 5ound one or two rows below the upper epidermis.
They are regularly arranged, elongated cells pac#ed with chloroplasts. This is
where most photosynthesis occursJ
• S'o$-! M%so'!** ! 5ound between the )al. 8es. and the lower epidermis.
ontain fewer chloroplasts and are irregularly arranged to allow the
movement of gases and water to the cells and stomates
• V%i$s ! Tubes of vascular tissues containing )hloem and 6ylem cells, which
transport materials to and from the leaf. 6ylem transports water and mineral
ions from the roots to the leaves, where as )hloem transports the products of
photosynthesis from the leaves to the rest of the plant. eins form a
branching networ#, giving rigidity, maintaining shape and structure, and
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 10/74
ensuring every leaf cell is close to a vein.
MAMMALIAN DIGESTION
THE DIGESTIVE SYSTEM
Animal cells are heterotrophic, so they cannot ma#e their own food, and must
obtain it from somewhere else.
The digestive system allows nutrients to be ta#en into the organism and
bro#en down and digested, converting large insoluble food molecules into
small, soluble ones that can be absorbed and made available to the cells.
• In mammals, digestion involves both mechanical, and chemical brea#down of
food by enzymes, followed by absorption into the body
HERBIVORES AND CARNIVORES COMPARED = MOUTH AND TEETH
• The action of teeth greatly increases the surface area of food, allowing them
to be bro#en down and absorbed faster
• 8ammals have K #inds of teeth, incisors and canines, used for cutting
Fprominent in carnivoresH, and molars and premolars, used for grinding
Fprominent in herbivoresH.
9EATURES O9 THE HUMAN DIGESTIVE SYSTEM
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 11/74
Mo" #$/ &o" c#)i! ! Teeth mechanically brea# food into pieces,
saliva lubricates food
E'i-*ois ! loses of the trachea so food goes down the oesophagus Fnot
the windpipeH
O%so'#-"s ! arries food to stomach
So&#c ! @egins the digestion of proteins and the food is churned. Thelength of time food spends in the stomach is related to diet. arnivores have
simple stomachs, whereas herbivores may have comple$ stomachs with food
remaining there for a long time
P#$c(%#s ! )roduces enzymes and neutralises acid
Li)%( ! )roduced bile which emulsi'es fats, and stores some products of
digestion
G#** B*#//%( ! 0tores bile
S&#** i$%si$% ! igestion is completed by enzymes from the pancreas and
the small intestine itself. 9utrients and water are absorbed
L#(-% i$%si$% ! "ater is absorbed with soluble compounds li#e vitamins
and minerals. ndigested food leaves body as feces. The c#%c"& is found
here, which is enlarged in herbivores as it is where bacterial fermentation of
plant material occurs. arnivores have a small c#%c"& and a shorter large
intestine as their food reuires little fermentation
5.> E7CHANGING GASES
GAS E7CHANGE IN ANIMALS
• All organisms respire, ta#ing o$ygen from the environment and releasing *
through the use of respiratory surfaces
• These surfaces must be thin, moist, and have a large surface area to allow
easy di(usion
INSECTS
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 12/74
• Insects have a system of tubes called (#c%#% within their body
• These tracheae open to the e$ternal environment through pores, or spiracles,
on the abdomen, allowing gas to be e$changed throughout the insect&s body,
bringing air directly to the cells
• The ending of the tracheae are called tracheoles and usually are 'lled with
+uid
9ISH
• 4espiratory surface is gills over which water +ows
• Two types/ e$posed and those covered by an operculum
• sually 'nely divided which means water +ows over a large surface area.
9ROGS
• Two respiratory surfaces ! Dungs and s#in
• *$ygen from air di(uses into moist s#in and is transported by blood to the
heart and then around the body
• Dungs are simple and have a smaller surface area than mammals, are more
li#e balloons than sponges and are less eLcient that mammalian lungs
MAMMALS
• ases e$changed in the lungs
• Dungs are protected by being inside the body&s waterproof covering
• 0urface area of lungs is increased by the convolution of the lungs into lobes,
the branching of the bronchioles, and the division of the tubules into tiny air
sacs called alveoli.
TRANSPORT SYSTEMS IN 9LO6ERING PLANTS
THE NEED 9OR TRANSPORT SYSTEMS
• Transport systems are used to ensure that cells are supplied with nutrients
and to e$pel waste.
• 8ulticellular organisms have these systems, enabling substances to be
moved to and from the internal body cells
• In +owering plants, long tubes run through the root, stem, and leaves. These
are the $ylem and phloem which each transport a di(erent substance
• "ater and minerals are transported up the plant in the $ylem and organicmaterials are transported both up and down by the phloem
6ATER TRANSPORT
• "ater and mineral ions +ow upwards through the plant, starting at the roots
and lost by transpiration
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 13/74
• The root hairs provide a large surface area for the upta#es of water, entering
by osmosis through the centre of the root and moving to the $ylem
• 6ylem vessels are dead cells thic#ened with woody material which form a
continuous system of tubes, giving strength ad rigidity to the stem. "ater
moves up the $ylem aided by conducting cells and is transported to the
leaves via the stem• The di(usion of water from a plant is called transpiration
• This occurs when the stomates open to e$change gases as the water di(uses
out due to uneven water concentrations of the plant and e$ternal
environment
• E$ternal factors which can a(ect transpiration include temperature, humidity,
wind, light, and soil
PHLOEM
• Transports sugars produced in photosynthesis around the plant
• 8aterials are transported both up and down the plant.
GASEOUS E7CHANGE IN PLANTS
STOMATES
• 0tomates are pores in leaves through ehich gases can di(use
• sually found on the lower surface of a leaf
• an open and close, determining whether gases can disuse or not, which in
turn a(ects the rate of photosynthesis and the transpiration rate
• uard cells control this opening and closing, becoming full of water, or turgid,
to open and losing water to close• 0tomates are usually open during the day and closed at night however guard
cells respond to a variety of di(erent internal and e$ternal stimuli, including/
light, low carbon dio$ide levels, an internal cloc#, water de'ciency, and high
temperatures
5.? GRO6TH AND REPAIR
MITOSIS
• 8itosois is the process by which a multicellular organism grows, repairs,
maintains, and reproduces itself
• It is a type of cell division that results in the production of cells which are
identical to the original
• It really ta#es place in two separate processes ! 8itosis, division of the
9ucleus, and yto#inesis, division of the cytoplasm
• )rior to mitosis, the cell&s KM chromosomes are copied, which are the
distributed during mitosis into each new cell as it forms
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 14/74
THE STAGES O9 MITOSIS
• Interphase ! The period when cells are not dividing, chromosomes are
duplicating, but not visible
• )rophase ! Each chromosome visible as two identical %oined strands called
chromatids. The nuclear membrane brea#s down by late prophase• 8etaphase ! 8icrotubles spread across the cell forming a spindle. The
chromosomes line up at the centre of the cell attached to the spindle 'bres at
the centromere. The chromatids separate
• Anaphase ! The chromatids, now single stranded chromosomes move
towards opposite poles, carried by the spindle 'bres
• Telophase ! The spindle disappears and new nuclear membranes form around
the two sets of chromosomes
•
THE NEED 9OR CYTO;INESIS
• yto#inesis usually happens immediately after mitosis, ensuring the
chromosome number in each cell remains constant
• The chromosome number doubles in mitosis and one cell now contains sets
of chromosomes, reuiring yto#inesis to occur so as to create two cells
SITES O9 MITOSIS
PLANTS
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 15/74
• In mature plants, mitosis mostly occurs in the tips of roots and stems, causing
an increase in length. It occurs in other places too but we don&t need to #now
that
INSECTS
• Instead of cell division FmitosisH, insects grow through cell enlargement and
therefore there are no sites of mitosis
MAMMALS
• In young mammals, mitosis rates are high and occurs in all areas of the body
• At maturity, growth decreases but the repair and maintenance of cells
continues
• In adults, it occurs in the s#in, bone marrow, and digestive system constantly
CHAPTER <: LI9E ON EARTH
<.1 THE ORIGINS O9 LI9E
THE PRIMEVAL EARTH
• There are ma%or theories on how life could have started on earth
PANSPERMIA
• The theory of )anspermia states that the chemicals for life came from outer
space
• 0cientists believe that the earth was heavily bombarded with meteorites
during the early years of formation
• "hen certain types of meteorites in the >BC?s were analysed, they were
found to contain organic molecules such as amino acids, the building bloc#s
for life
• This provided evidence of the e$istence of organic molecules somewhere else
in the cosmos and shows how meteorites falling on earth during it&s early
formation could have contributed to some of the organic molecules reuired
by living systems
CHEMOSYNTHETIC 9ORMATION ON EARTH
• 5irst suggested by *parin and 7aldene, who theorized that the early
atmosphere of earth contained all the necessary chemical components for life
to form, hypothesizing that more comple$ organic molecules, such as Amino
Acids, could have been created in spontaneous reactions using energy from
4ays or lightning.
• 7owever, this theory remained untested until the >B2?s when two scientists,
rey and 8iller, performed an e$periment based on the hypothesis
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 16/74
• A closed system was set up and powerful electrical spar#s Fsimulating
lightningH were discharged into a chamber containing ammonia, hydrogen,
and methane; three gases thought to have been prominent in the early
atmosphere
• After a wee# of continuous discharges and recycling of steam, the condensed
water in the +as# set up under the e$periment became red and turbid, andfound to contain a number of amino acids
• This supported *parin and 7aldene&s theories and showed how organic
molecules could have formed naturally in the conditions of early earth
CHANGES IN TECHNOLOGY
• *ur ability to describe the origins, processes, and evolution of living this has
been made possible in advances in science and technology, with new
techniues to 'nd more about earth, it&s history, and the living organisms
that occupy it bring developed
• The most important in the study of early earth is the development ofradiometric dating, which allows scientists to determine the age of roc#s and
fossils bac# to the formation of earth
• evelopment of the electron microscope has also played an in+uential role in
the #nowledge of cells and their structure and function, enabling scientists to
compare di(erent organisms and see how they function
• These new technologies lead to a better understanding of the origins of life
and the evolution of living things
<.5 9OSSILS AND THE EVOLUTION O9 LI9E
MA@OR STAGES IN THE EVOLUTION O9 LI9E
>. The formation of organic molecules. The formation of membranes1. )rocaryotic cells ! 0imple structuresK. Eucaryotic organisms ! 9ucleus and organelles developed2. olonial cells ! 5ound in stromatalitesM. 8ulticellular organisms ! 0how specialization of function evolved
PALAEONTOLOGICAL AND GEOLOGICAL EVIDENCE O9 EARLY LI9E
PALAEONTOLOGICAL EVIDENCE
• Evidence of early life can be found in fossils however is scarce compared to
over the past M?? years
• Earliest fossils are found in two types/ microfossils, and stromatalites which
are layered mats of photosynthetic pro#aryotic cells called cyanobacteria
• escendents of these cyanobacteria can still be found in "estern Australia
• These fossils can be found in roc#s over 1K?? million years old
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 17/74
GEOLOGICAL EVIDENCE
• The 'rst cells were heterotrophic, however as the developed they gained
pigments and were able to capture light energy from the sun and use it to
convert * into o$ygen
•
As more photosynthetic organisms developed, more * was converted into*$ygen, which started to be ta#en up by roc#s
• These o$idized roc#s can be seen in banded iron formations and red bed roc#
formations today
S;IPPED: THE CHANGING ATMOSPHERE
<.< PROCARYOTES: THE 9IRST LIVING THINGS
6HAT ARE PROCARYOTIC ORGANISMS
• @elieved to be the 'rst type of cells to evolve on Earth about 1?2? million
years ago• 0till the most abundant life form on earth
• i(er from eu#aryotic cells as they lac# a nuclear membrane and internal
organelles
• Technological advances in electron microscopy have increased our #nowledge
of pro#aryotic organisms, such as the discovery of two di(erent types of
pro#aryotes/ Archaea and Eubacteria
<.> TA7ONOMY: CLASSI9YING ORGANISMS
6HY CLASSI9Y
• lassi'cation systems help biologists to understand the relationship between
organism, and to tal# to other biologists about organisms without the need to
describe them in detail
9EATURES USED TO CLASSI9Y ORGANISMS
• Anatomy FstructureH, physiology FfunctioningH, behavior FdoingH, and
biochemistry Fmolecular activityH are the ways organisms can di(er, and
using these features as a guideline, biologists can easily classify organisms
• The most practical in the 'eld is anatomical structure, as it is easily observed
and more constant in an organisms lifetime• 7owever structure is not always reliable, as organisms which loo# the same
may not always be closely related, for this reason the molecular structure, or
9A, is increasingly being used by biologists to classify organism
CLASSI9ICATION SYSTEMS
The most common classi'cation system recognizes 2 #ingdoms/
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 18/74
• )lants ! organisms which contain chlorophyll and ma#e their own food.
Eucaryotic and have a cell wall
• Animals ! o not contain chlorophyll, cannot ma#e own food, eu#aryotic, no
cell wall
• )rotists ! 0ingle celled, eu#aryotic Feg. )rotozoansH
• 8onera ! 0ingle celled, pro#aryotic Feg. @acteriaH• 5ungi ! o not contain chlorophyll, eu#aryotic, surrounded by a cellulose cell
wall
LEVELS O9 ORGANISATION
*nce Ningdom is determined, there are M other levels in which an organism is
classi'ed. These are/ )hylum, lass, *rder, 5amily, enus, and 0pecies
ADVANCES THROUGH TECHNOLOGY
• evelopment on light and electron microscopes dramatically in+uenced
scientist&s ability to view cells and di(erentiate and classify organisms
• Advances in molecular biology and biochemistry aided in the discovery of the
two main groups of 8onera F)rocaryoticGEucaryoticH
• 9A and molecular comparison tec$hniues to accurate classify organisms
based on their genetic structure rather than appearance, adding to out
#nowledge of relationships between organisms and helping to re'ne the
classi'cation system
THE BINOMIAL SYSTEM
• This classi'es organisms with two given names, the 'rst being the enus,
and the second being the 0pecies of the organism
• enus always starts with a capital and species always starts with a lowercase
Feg. @an#sia coccineaH
S;IPPED: DICOTOMOUS ;EYS
CLASSI9YING E7TINCT ORGANISMS
• 5ossil remains are not always diLcult to classify, however problems arise
when the fossil is incomplete or does not show enough detail to accurately
assess the structure of the organism
• )roblems also arise if the organism has been e$tinct for a long time as theremay be no similar organisms alive today to compare it with
CHAPTER >: EVOLUTION O9 AUSTRALIAN BIOTA
>.1 GOND6ANA: ANCIENT SUPERCONTINENT
THE 9ORMATION O9 AUSTRALIA
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 19/74
• Australia became a separate continent K2 million years ago, splitting o( from
ondawana, which in turn split o( from )angea, an ancient supercontinent
about >M? million years ago
GEOLOGICAL EVIDENCE
• The roc# strata around the continental margins, match perfectly in many
places, such as between 0outh Australia and one section of Antarctica
• The ages of roc#s near mid-ocean ridges indicates a continual movement of
the plates, as the closer to the ridge, the younger the roc# is
BIOLOGICAL EVIDENCE
• 5ossil evidence shows similar organisms on continents thought to be part of
ondwana as those found in Australia
• Diving species are also similar in some parts of the world which are believed
to be part of ondwana, particularly southern beech trees, found in Aust, 9O,
9ew uinea, and 0th America
AUSTRALIAS MEGA9AUNA
• In simple terms, megafauna are large animals which have mostly all gone
e$tinct over the last 2???? years, apart from such animals as the elephant
and whales
• There are two main theories to e$plain this rapid e$tinction/
• limate change/ 8uch e$tinction occurred at about the end of the last Ice
age, an event which drastically changed the ecosystem. In Australia, the
weather changed from cold and dry to warm and dry, meaning the water
became scarce and unable to sustain life for such large animals
• 7uman e$pansion/ The megafauna were big and slow, therefore vulnerable to
hunting, in particular the arrival of s#illed hunters. It is thought that the rapid
e$tinction of many Australian megafauna occurred soon after humans arrived
in Australia for the 'rst time
• It is li#ely that both these factors played a part in the e$tinction of these
species
• Today, relatives of the megafauna survive, such as the red #angaroo to the
Procoptodon pusio and the Diprotodon optatum to the wombat
• The megafauna were not descendants of Australia&s current fauna however,
they both evolved from a common ancestor
>.5 CHANGES IN AUSTRALIAN 9LORA AND 9AUNA
VARIATION 6ITHIN A SPECIES
• ariations are small di(erences between organisms belonging to the same
species
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 20/74
• This can include di(erences in size and colour, as well as biochemical
di(erences
• These di(erences become important in evolutionary terms as when
environmental change occurs, those with di(erent variations may be able to
survive
S;IPPED: AUSTRALIAS CHANGING ENVIRONEMENT THE AUSTRALIAN
ENVIRONMENT CHANGES IN THE DISTRIBUTION O9 SPECIES
CHARLES DAR6IN IN AUSTRALIA
• "hilst in Australia, arwin was puzzled over the variety of organisms present
in Australia, spending a long time studying them
• @y comparing species found in Australia to those found in England and 0outh
Africa, arwin supported his theory that new species of an organism can
develop from a common ancestor and that those best suited to the
environment were more li#ely to survive and prosper
>.< THE CONTINUATION O9 A SPECIES
MEIOSIS
• 8eiosis is a type of cell division that forms cells with half the number of
chromosomes normally found in cells of the species and is associated with
se$ual reproduction
• In reproduction, an organism produces types of special se$ cells called
gametes, a male gamete and a female gamete
• "hen a male gamete and a female gamete from two di(erent organisms
come together, they fuse in a process called fertilization which results in a
zygote
• This zygote is single celled and undergoes mitosis to eventually form a new
individual
• In humans, cells normally contain KM chromosomes, this is #nown as our
diploid number
• "hen meiosis occurs, this number is halved to 1 chromosomes, our haploid
number
• The number of chromosomes is halves so that when two haploids meet, they
ma#e a diploid cell, the 'rst cell of a new individual
• 8ales produce haploid gametes called sperm, females produce haploidgametes called ova
S;IPPED: 9ERTILISATION: BRINGING GAMETES TOGETHER
SE7UAL REPRODUCTION IN 9LO6ERING PLANTS
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 21/74
• 5lowers are the reproductive organs of angiosperm plants, with di(erent parts
of the +ower serving a di(erent purpose for reproduction
MALE REPRODUCTIVE ORGANS
• The male reproductive organ is called the stamen, which consists of the
anther and the 'lament
• There are usually several stamens in a +ower
• 8eiosis occurs in the anthers and results in the formation of haploid Fhalf a
diploidH pollen grains which in turn has a protective wall and contains two
haploid nuclei
9EMALE REPRODUCTIVE ORGANS
• The female reproductive organ is the pistil, which consists of one or more
carpels which contain and stigma, style, and an ovary
• Inside the ovary is several ovules, this is where meiosis occurs, resulting in
the formation of P haploid cells, one of which is an ovum, or egg
POLLINATION AND 9ERTILISATION
• )ollination is the transfer of pollen from a stamen FmaleH to a mature stigma
FfemaleH. If this occurs, fertilization can ta#e place
• 5ertilisation occurs as/ A germinating pollen grain sends out a tube which
grows down the style towards the ovary The two nuclei of the pollen grain
travel down this tube *ne becomes the tube nucleus, the other divides in
two The pollen tube enters the ovule through the micropyle *ne male
nuclei fuses with the ovum to form a fertilized zygote The other fuses with
two other haploid nuclei to form a triploid
SEL9 POLLINATION AND CROSS POLLINATION
• If pollination involves pollen and stigma from the same plant it is #nown as
self pollination
• ross pollination is when pollen from one plant is transferred to a stigma on
another plant of the same species
• 0elf pollination is an e(ective way for +owers to breed uic#ly and eLciently,
however it gives no rise to variation, meaning that there is a higher li#elihood
of mass death in the case of a disease or environmental change
POLLINATION BY ANIMALS
• 8any Australian +owers are pollinated by insects, birds, and mammals
• 0ome +owers have colours and scents which are appealing to insects such as
bees and wasps so that pollination has a higher rate of occurrence, for
e$ample the colour yellow attracts bees see#ing nectar
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 22/74
END O9 PRELIMINARY COURSE
CHAPTER ?: MAINTAINING A BALANCE
?.1 ACTIVITY AND TEMPERATURE
THE ROLE O9 ENYMES
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 23/74
• All chemical processes occurring within an organism are called its metabolism
• The rate of chemical activity is regulated by enzymes, large proteins
• Enzymes are used over and over again, so cells do not reuire a large
uantity
• They are made in the cell, their manufacture controlled by the nucleus
• i(erent types of cells ma#e di(erent enzymes
9UNCTIONS AND CHARACTERISTICS O9 ENYMES
• Enzymes are biological catalysts, they control the rate of reaction
• Enzymes are speci'c, they a(ect one type of reaction, providing an active
site where it can ta#e place
• Enzymes act on molecules #nown as substrates Feg. atalaseH
• The substrate binds to the active site, causing a temporary change in the
shape of the enzyme, #nown as the induced 't model
• A chemical reaction occurs on the active site and the substrate molecule
splits• The substrate concentration a(ects enzyme activity, Q 0ubstrate R QActivity,
9TID all enzyme active sites are occupied, #nown as the saturation point
• Enzymes reuire speci'c conditions to function most eLciently, temperature
and acidityGal#alinity playing a huge role in how eLcient the enzyme
functions
• Too far from functioning conditions and the enzyme is <denatured=, the active
site warping, and can no longer catalyse reactions
HOMEOSTASIS
• 7omeostasis is the process by which organisms maintain a relatively constantor stable internal environment for body cells
• It consists of/ detecting changes FreceptorH, and counteracting changes
Fe(ectorH
• 7omeostasis is essential for the correct functioning of enzymes
RESPONDING TO CHANGE
DETECTING CHANGES
• Any information that provo#es a bodily response is called a stimulus
•
Environments contain many stimuli and organisms have receptors that detectthem
• Eg. Dight-S)hotoreceptor, 7eat-SThermoreceptor, *$ygen-Shemoreceptor
COUNTERACTING CHANGES
• "hilst receptors ETET changes, organisms too reuire a response to the
change, which is brought by the e(ectors
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 24/74
• Eg of e(ectors R muscles, glands
• To co-ordinate this sensory information, the body uses the nervous system
THE HUMAN NERVOUS SYSTEM
• The nervous system is made up of; the central nervous system, the brain,
and the spinal cord
• This system acts as a control centre which co-ordinates all an organism&s
responses
• It receives information FreceptorsH, and initiates a response Fe(ectorsH
TEMPERATURE AND LI9E
• The temperature of an environment is #nown as the ambient temperature
• To survive, organisms must be able to live within the temperature range of
their environment
ECTOTHERMS AND ENDOTHERMS
• Ectotherm ! An organism which has limited ability to control their body
temperature, their cellular activities generate little heat. Their body
temperature rises with the ambient temperature. Eg. )lants, amphibians, 'sh,
reptiles
• Endotherms ! An organism which maintains their body temperature though
metabolism, independent of the ambient temperature. This ta#es more
energy and so more food is reuired for endotherms. Eg. 8ammals, birds
BEHAVIOURAL ADAPTATIONS TO TEMP CHANGEF
• 8igration ! Animals move to avoid temperature e$tremes
• 7ibernation ! Animals remain in a sheltered spot and lower their metabolism
• 0helter ! Animals see# shelter from e$treme conditions
• 9octurnal Activity ! Animals sleep during day and are active at night
• ontrolling E$posure ! Animals alter their position to e$pose more or less
surface area to sunlight
STRUCTURAL AND PHYSIOLOGICAL ADAPTIONS O9 ENDOTHERMS
• Insulation ! 5ur and feathers, as well as fat #eep organisms warmer in the
colder months, and can be shed in the hotter months to remain cool
• 8etabolic Activity ! Endotherms generate heat as a result of their metabolic
activity. This #eeps the body warm in cold conditions.
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 25/74
• ontrol of @lood 5low ! Endotherms can increase or decrease heat e$change
by controlling blood +ow to the s#in and e$tremities, maintaining a core body
temp
• Evaporation ! @y controlling evaporation of water from their bodies,
endotherms #eep themselves cool. Eg Nangaroos lic# their paws to increase
evaporation therefore increase heat loss
?.5 6ATER 9OR TRANSPORT
THE MAMMALIAN CIRCULATORY SYSTEM
• 8ammals have a closed system, comprising of a pump Fthe heartH, which
sends a +uid Fthe bloodH through a networ# of tubes Fblood vesselsH which
transport it around the body
• @ody +uid drains into the lymphatic system and the lymph vessels return the
+uid to the blood
•
The circulatory system is used for transport of water, gases, and nitrogenouswastes, defence against disease, and to distribute heat around the body
COMPOSITION O9 THE BLOOD
• 8ammalian blood is made up of )lasma, and ellular 8atter
• )lasma ! 8ade up of mostly water, contains some chloride ions and large
plasma proteins. These salts and proteins play a role in maintaining the p7 of
the blood. )lasma also carries urea, carbon dio$ide, products of digestion,
and hormones
• 4ed @lood ells ! ontain the pigment haemoglobin, helping them to perform
their main function/ carrying o$ygen and gases to the cells. In humans, 4@shave no nuclei and remain in the blood for about 1 months before being
destroyed and replaced.
• "hite @lood ells ! About double the size of 4@s, come in two types/
phagocytes and lymphocytes. )hagocytes can move from blood to tissue +uid
and are a vital part of the immune defence, surrounding and destroying any
foreign body that enters the body. Dymphocytes act against foreign material,
creating antibodies.
• )latelets ! Aid in helping the blood to clot
TRANSPORTING SUBSTANCES IN THE BLOOD
0ubstance 5rom To 5orm arried @y*$ygen Dungs @ody
ells
*$yhaemoglobin 4@s
arbon io$ide @ody ells Dungs 8ainly 7ydrogen
arbonate Ions
F@icarbonate
4@s and
)lasma
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 26/74
IonsH
"aste 9itrogenous
8aterial
Diver and @ody
ells
Nidneys 8ostly as rea )lasma
"ater igestive
0ystem and
@ody ells
@ody
ells
"ater 8olecules )lasma
0alts igestive0ystem and
@ody ells
@odyells
Ions in the)lasma
)lasma
THE STRUCTURE O9 BLOOD VESSELS
@lood +ows through a system of tubes or vessels, under the in+uence of the
nervous system which control the +ow and distribution of blood
There are three types of blood vessels/
Arteries ! arries blood from the heart to the cells, thic# walled, elastic, and
muscular. Elastic 'bres allow the vessels to e$pand and recoil with eachheartbeat, maintaining pressure on the blood, sending it in spurts to body
tissues. @y e$panding and contracting, they push blood around the body.
apillaries ! *nly one cell thic#, around C micrometres, so blood cells must
pass through single 'le. apillaries surround tissue cells so no cell is far from
a capillary. 7ave a large surface area to allow e$change of materials between
blood and body cells
eins ! 4eturn blood from the cells to the heart. The walls are thinner and less
muscular than that of arteries, and have a larger diameter. The blood +ows
with much less pressure and so valves, which prevent the bac#+ow of blood,
are present in veins.
The 7eart ! Acts as a pump which #eeps blood circulating in the body.
onsists of the left and right atria FatriumH, and the left and right ventricles.
The atria receive blood from the veins, and the ventricles send blood around
the body through the arteries. The heart aids in the e$change of gas, blood
pic#ing up o$ygen here as it beats around M?-P? times per minute
The )ulmonary ircuit
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 27/74
TRANSPORT MECHANISMS IN
PLANTS
• )lants have two transport systems;
the phloem and the $ylem
• The phloem transports organicmaterials, such as sugars, up and
down the stem to other parts of the
plant
• The $ylem transports water
and mineral ions up from the roots to
the leaves
THE STRUCTURE O9 7YLEM
• The $ylem of +owering plants
consists of $ylem vessels, tracheids, 'bres, and parenchyma
• essels may be up to several metres in length, and as they develop, lignin
Fdead woody cellsH is deposited in their cell walls in a spiral pattern,
strengthening the $ylem vessel and ma#ing it impermeable to water
• "ater enters the plant through the root hairs, travelling across the corte$ into
the $ylem
• "ater can rise in the $ylem at a rate of >2 metres per hour, against gravity
• This rising is brought on by the passive upwards movement brought on by the
pull of the transpiration stream through the stomates.
• "ater is drawn up the $ylem tubes to replace the loss of water throughevaporation
• The branching networ# of $ylem vessels ensures water is transported to all
parts of the plant
• 7owever as the water is pulled upwards some may lea# out into surrounding
tissues or another vessel
• Adhesion-ohesion forces also aid in the water climbing& up the $ylem to the
leaves
THE STRUCTURE O9 PHLOEM
• The phloem of +owering plants contains phloem 'bres, phloem parenchyma,sieve cells, and companion cells
• 0ieve cells are elongated cells which form a series of connecting tubes
• 0ieve cells aid in the transport of carbohydrates from the phloem to the plant
• ompanion cells are lin#ed to the sieve cells and ta#e on many metabolic
functions for the sieve element
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 28/74
• *rganic materials, including sugars, amino acids, and hormones are
transported by the phloem in a movement #nown as translocation
• Translocation enables a plant to distribute resources wherever needed in the
plant
• <0ource-to-sin#= or the <)ressure 5low= depositing of materials created by
photosynthesis into the roots• Amino acids and mineral nutrients are loaded into the phloem at the source
of photo synthesis, the leaves
• These materials then +ow towards a <sin#=, the region on a plant where
sugars and nutrients are being actively removed from the phloem, eg. The
roots, stems, and +owers
• The materials are then used in metabolism or stored in the plant, glucose as
starch
?.< REGULATION O9 SUBSTANCES
6ATER IN CELLS
• "ater is a solvent for all metabolic reactions and is the transport medium for
distributing substances in the body
THE REMOVAL O9 6ASTES
• As a result of all the metabolic functions occurring in the body, wastes are
created
• If these wastes were allowed to accumulate in cells, it would slow down
metabolism and poison the cells, therefore these wastes need to be removed
uic#ly
• i(erent animals e$crete di(erent waste products
THE ROLE O9 THE ;IDNEY
• The primary role of the #idney is to regulate salt and water concentrations in
the body, and e$crete nitrogenous wastes
• 8ammals e$crete the nitrogenous waste urea
• 5ish e$crete ammonia, coupled with much larger amounts of water Fin
freshwater 'shH
THE 9ISH ;IDNEY
• The primary role of the #idney is the regulation of water and salt
concentrations in the body
• In 'sh, e$cretion of nitrogenous wastes, such as ammonia, occurs across the
gills
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 29/74
• The #idneys ad%ust the levels of water and mineral ions in the 'sh&s body in
order to maintain a constant concentration of internal +uid
9RESH6ATER 9ISH
• 5reshwater 'sh maintain a higher concentration of solutes in their body than
in their surroundings
• Therefore, water tends to continually di(use into the 'sh&s body, which it
must then get rid of
• Their #idneys produces large amounts of e$tremely diluted urine in an almost
continuous stream to do this
• As fresh water has a lower concentration of ions than the 'sh do, the #idneys
actively reabsorb salts to prevent loss
SALT6ATER 9ISH
• 0alt water 'sh have the opposite problem to freshwater/ their internal body
+uids are less concentrated than the surrounding water
• To avoid water loss, marine 'sh continually drin# salt water, absorbing both
the water and the salts
• The water is retained and the salts are e$creted via the gills and #idneys
• ue to this lac# of water availability, salt water 'sh e$crete much less urine
that freshwater, and is much more concentrated to minimise water loss
RENAL DIALYSIS
• 4enal dialysis is the arti'cial process in which wastes in the blood are
removed by di(usion across a semi-permeable membrane
• ialysis helps those whose #idney function is so impaired that products of
metabolism, such as urea, are built up in the body instead of e$creted
• If both #idneys stop wor#ing due to disease, the patient&s life is immediately
threatened, ma#ing renal dialysis e$tremely important.
•
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 30/74
THE MAMMALIAN ;IDNEYS
• The Nidneys are compacts and bean shaped
• They produce urine, which contains nitrogenous materials from the cells
• rine leaves the #idneys from the ureters and is stored in the bladder until
being e$creted• 8ammals have two #idneys
• Each is made up of around a million small 'ltering units called nephrons
•
•
• The #idneys continuously process an enormous volume of blood to form a
small volume of urine
• There are three processes in the formation of urine/ 'ltration, reabsorption,
and secretion
• 9i*(#io$ ! @lood is brought to the #idneys by the renal artery, which divides
into smaller vessels which after reaching the @owman&s apsule, form a
networ# of capillaries called the glomerulus. 5rom the glomerulus, plasma
and small soluble molecules pass into the @owman&s apsule through passive
'ltration, and the 'ltrate contains some substances which may be reabsorbed
and used by the body, and some wastes. As the substances are moved along
)at 4ussell ! 0t 5rancis 6avier ollege
iagram of a
9ephron
iagram of a Nidney
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 31/74
the nephron tubule, its composition is ad%usted until it only contains wastes,
after which it is e$creted as urine.
• 5iltrate passing into the @owman&s apsule may include/ water, nitrogenous
wastes, food materials, bicarbonate ions, hormones, and ingested substances
such as penicillin
•R%#so('io$ ! 0urrounding each nephron is a large capillary networ#. Asthe 'ltrate travels down the tubule, materials that can be reused are
reabsorbed into the blood, such as glucose, amino acids, and water. It is an
active process which reuires energy and ta#es place most notably in the
loop of 7enle
• S%c(%io$ ! A selective process by which the body transports substances
from the blood to the nephron
REGULATION O9 BODY 9LUID COMPOSITION
• The nephron is a regulatory unit, it reabsorbs materials reuired to maintain
homeostasis• This regulation helps to maintain the constant composition of the blood and
intestinal +uid
• In the pro$imal tubule, bicarbonate ions F*H are reabsorbed and there may
be some secretion of hydrogen ions, this is done to maintain a constant blood
p7 level
• The loop of 7enle is involved in the 'ltration and reabsorption of water
ACTIVE AND PASSIVE TRANSPORT
• *smosis and di(usion are passive forms of transport across cell membranes,
that is they don&t reuire energy• In the #idneys, both active and passive transport is used
• )assive transport occurs in 'ltration and osmosis of water bac# into blood
• Active transport occurs in secretion of substances into the nephron, transport
of nutrients bac# into the blood, and selective reabsorption of salts
THE ENDOCRINE SYSTEM AND HORMONES
• The endocrine system consists of ductless glands which secrete hormones;
chemical messengers that travel in blood
• 7ormones bring about change in the metabolic activity of the body and are
#ept at a fairly constant level by feedbac# systems
4ole escriptionontrol of the Internal
Environment
7ormones maintain homeostasis by regulating the
amounts and type of many body chemicalsEmergencies 7ormones enable the body to cope with stress !
physical or emotionalrowth 7ormones ensure growth and development ta#e place
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 32/74
in a smooth, controlled way4eproduction 7ormones are involved in reproduction from gamete
formation to maintenance of the placenta, birth and
nourishment of the newborn
HORMONAL REGULATION O9 6ATER AND SALT LEVELS
• Two hormones; antidiuretic hormone FA7H and aldosterone, help to regulate
salt and water concentrations, as well as blood pressure and volume
• The blood that leaves the #idney via the renal vein has had its nitrogenous
wastes removed and its water and salt composition balanced
• The function of the #idney is twofold/ it acts as an e$cretory organ, and has a
homeostatic function, helping to maintain a constant internal composition of
body +uids
ANTIDIURETIC HORMONE ADHF
• 4eabsorption of water is controlled by A7
• A7 is made by the hypothalamus but is stored in the pituitary gland
• 4eceptors in the hypothalamus monitor the concentration of the blood/ if
there is a loss of water, A7 is released into the blood and circulates to the
#idneys
• A7 increases the permeability of the walls of the distal tubules, allowing
water to pass freely out of the tubules bac# into the body
• As the blood returns to normal concentration by negative feedbac#, less A7
is secreted
• If blood concentration is low, after a lot of water has been drun#, less A7 is
released and the permeability of the distal tubules is decreased, allowing
more water to be passed as urine
ALDOSTERONE
• Aldosterone regulates the amount of salt in the body
• It is produced in the adrenal glands, situated above the #idneys
• If there is an increased blood volume and blood pressure, resulting from high
salt concentrations, to output of aldosterone is reduced
• Dess salt and water is reabsorbed by the nephron tubules and increased
amounts of salt and water are lost in the urine
• If the body needs salt, water is not retained, the adrenals release more
aldosterone, and salt is reabsorbed from the tubule
ENANTIOSTASIS: SURVIVAL IN AN ESTUARY
6HY IS AN ESTUARY SPECIAL
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 33/74
• An estuary forms where a river meets the sea, fresh water draining from the
land mi$es with saline water from the sea
• Estuaries are rich, productive ecosystems which act as nutrient traps
• The sediment traps provide a rich soup& that supports a vast community of
organisms
• The water is calmer and more shallow than the sea and there is plenty of lightfor photosynthesis
• Estuaries are used by many species of 'sh as uiet breeding and nursery
places for their young
• 7owever there is a salinity gradient in an estuary, the salinity +uctuating
greatly as the tide goes in and out
• Enantiostasis is the maintenance of metabolic and physiological functions in
response to variations in the environment, and it is this process which helps
organisms survive in this environment of +uctuating salinity
• 7owever it is not alone, behavioural adaptions playing a role in survival in
estuaries
• 5ast swimming animals can move away, molluscs can close their shells,
bottom dwellers can burrow deep into the mud or sand
MAINTAINTING SALT CONCENTRATIONS IN PLANTS
• )lants, unli#e animals, cannot move away from the +uctuating conditions in
an estuary, and so must 'nd ways to cope with a high salt environment !
these plants are #nown as halophytes
• Three mechanisms which enable halophytes to control their salt levels are;
salt e$clusion, salt e$cretion, and salt accumulation
• 0alt e$cluders prevent entry of salt into their roots through 'ltration, a
passive process
• 0alt e$creters have special glands, usually in the leaves, where salt is
concentrated and actively secreted, which is then washed o( by rain
• 0alt accumulators concentrate salt in a part of the plant, usually bar# or old
leaves, and then drop that part of the plant o(, losing the salt
MINIMISING 6ATER LOSS IN PLANTS
• 6erophytes are plants adapted to dry conditions, there adaptions include/
S("c"(#*
• Deaves with a thic#, wa$y cuticle to reduce water lost by evaporation
• 4educed leaf surface area
• 4e+ective leaf surfaces
• 7airy leaves, which reduce air+ow across the leaf to reduce evaporation
• 0un#en stomates or a reduced amount of stomates
• 4olled up leaves to minimise water loss
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 34/74
P!sio*o-ic#*
• ertically hanging leaves that change position with the sun to reduce heat
absorption and water loss
• The closure of stomates during the hottest part of the day
•
ormancy period where all above-ground parts die o( • Tough, hard seeds that can survive long dry periods
• Tolerance to drying out
CHAPTER : BLUEPRINT O9 LI9E
.1 THE EVIDENCE 9OR EVOLUTION
ENVIRONMENTAL CHANGE
• Evolution is the change in living organisms over many generations
• Evolution can be caused by changes in an organism&s environment, such as
temperature changes or changes in water salinity, or by competition fromother organisms, such as competition for 'nding food and water
EVIDENCE 9OR EVOLUTION
PALAEONTOLOGY
• )alaeontology is the study of fossils, and can provide evidence for how
organisms have changed over time
• Transitional forms are e$amples of organisms that indicate the development
of one group of organisms from another or from a common ancestor, which
can be seen in the fossil record
BIOGEOGRAPHY
• @iogeography is the study of the distribution of living things/ where certain
animals and plants are found in the world
• 5or e$ample, the animals and plants found in Australia are vastly di(erent to
those found in Asia
• @y loo#ing at the pattern of distribution of an organism today, plus its fossil
distribution in the past, we are able to reconstruct its evolutionary history
COMPARATIVE EMBRYOLOGY
• omparative embryology is the study of embryos of di(erent organisms,
loo#ing for di(erences and similarities between them
• A similarity between embryos suggests that the organisms came from a
common ancestor
COMPARATIVE ANATOMY
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 35/74
• omparative anatomy is the study of the di(erences and similarities in
structure between di(erent organisms
• The structures which the organisms have in common are evidence of similar
inherited characteristics from common ancestors
• An e$ample of this is the )entadactyl Dimb, a similar basic pattern in the
bones of arms and legs shared by most land vertebrates
BIOCHEMISTRY
• @iochemistry is the study of similar molecules between di(erent organisms,
which suggests genetic closeness
• 8olecules such as haemoglobin, 49A, and hormones are studied
• "hen studying proteins, amino acid seuences are compared, and if similar,
are a clue to genetic relationships eg. 7umans and himps
• 0tudy of blood and its compatibility when mi$ed is also used within
biochemistry, with closely related organisms displaying a small antigen-
antibody reaction when e$posed to foreign blood• Today these lin#s can be studied directly using 9A seuencing to compare
the bases and 'nd similarities
DNA HYBRIDISATION
• 9A hybridisation can be used to identify similarities in 9A structure
• 0pecies which show a high degree of hybridisation are e$pected to have
diverged recently from a common ancestor as the seuences will be very
similar• The process has K steps/
>. Two strands of 9A are separated by heat. The single strands formed are mi$ed with single strands from another
species1. The two di(erent strands will %oin to form a hybrid molecule, however not
all bases will match due to di(erencesK. The degree of pairing depends on this similarity between seuences, if it
'ts well there is a high degree of pairing, and so the organisms show close
relation
OTHER EVIDENCE 9OR EVOLUTION
THE AGE O9 THE EARTH
• 0cientists believe life on Earth has e$isted for over 12?? million years
• uring this time, continents have changed places and environmental
conditions have changed
• @y dividing this time into geological eras and periods the evolution of living
organisms can be traced
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 36/74
DOMESTICATED ANIMALS AND CULTIVATED PLANTS
• 7umans have been successful in breeding specialised animals and plants,
selecting the variations they prefer, demonstrating how evolution could have
occurred
EVOLUTION BY NATURAL SELECTION
>. In any population, there are variations between individuals. In any generation, there are o(spring that do not reach maturity and
reproduce; the characteristics of these organisms are removed from the
population1. Those organisms that survive and reproduce are well adapted to that
environment, they have favourable variationsK. These favourable variations are then passed on to o(spring and become
more common in the population
CONVERGENT EVOLUTION
• onvergent evolution occurs when natural selection over many generations
results in similar adaptions in species which live in similar environments
• 5or e$ample, seals and dolphins have much the same adaptions F+ippers,
strong swimmers, can hold their breath etc.H yet belonging to di(erent orders
of mammals
• espite being vastly di(erent animals, they e$hibit similar variations
DIVERGENT EVOLUTION
•
ivergent evolution Falso #nown as adaptive radiationH is the process thebegins with one species Fcommon ancestorH and produces organisms that
loo# di(erent from each other because they have evolved from isolated
populations in di(erent environments
• The most famous e$ample of divergent evolution is harles arwin&s
alapagos 5inches, >K species of 'nches displaying di(erent variations, but
who evolved from a common ancestor
.5 MENDEL AND THE INHERITANCE O9 CHARACTERISTICS
VARIATION: ENVIRONMENT OR INHERITANCE
There are two causes of variations in populations Fand by e$tension,
evolutionH/ Environment and inheritance
Environmental variation occurs because of the conditions that an organism
e$periences during its lifetime, for e$ample an animal may be small because
it has been unable to 'nd food
Environmental variation can change during an organisms lifetime
Inheritance however, is '$ed for the life of the organism
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 37/74
Each trait has a speci'c gene and each individual possesses a uniue
combination of these genes
MENDELS E7PERIMENTS
The 'rst studies of inheritance were carried out by regor 8endel in the
>P??s using the garden pea
7e published his 'ndings in >PMM, however is was totally ignored, and the
signi'cance of his wor# was not fully realised until the beginning of the ?th
entury
6HY DID MENDEL SUCCEED
8endel was very luc#y in the sense that the pea plant is a perfect sub%ect for
the C tests he undertoo#
7e studied seven di(erent characteristics in pea plants/ seed shape, seed
colour, pod shape, pod colour, +ower colour, height, and type of +owers
@efore testing, he pure-bred his plants, ma#ing sure the characteristic was
consistent
7e then deliberately and carefully crossed one variety with another,
pollinating by hand and removing stamens to eliminate self-pollination
7e repeated this process many times, #ept careful records, and used
mathematics to improve and record his studies and 'ndings
MENDELS E7PLANATIONS
DOMINANT AND RECESSIVE GENES
"hilst most people in 8endel&s time believed that inheritance occurred by<blending= FTall 0hort R 8ediumH, 8edel determined that there were two
forms/ dominant and recessive
Even though 8endel had no #nowledge of chromosomes, he came to the
conclusion that the units of inheritance which control a characteristic must
come in pairs, one received from each parent and combine at fertilisation
8endel called these units <inheritance factors=, but today we call them genes
Each individual has a pair of genes for each characteristic
The members of the gene pair are called alleles
"hen we refer to all the genes of an organism, we tal# about its genotype
"hen we refer to the appearance of an organism, we tal# about itsphenotype
*rganisms with identical genes in their pair Feg. TT, or ttH are called
homozygous
*rganisms with di(erent genes in their pair Feg, TtH are called heterozygous
MENDELS LA6S
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 38/74
• 8endel summarised his wor# to e$plain the inheritance of characteristics in
two laws
• The 'rst law, The Daw of 0egregation, states that factors for the same
characteristic occur in pairs in an individual. These pairs separate at gamete
formation, so that a gamete contains only one of each factor
.< CHROMOSOME STRUCTURE = THE ;EY TO INHERITANCE
THE IMPORTANCE O9 CHROMOSOMES
In >B?, it was suggested that 8endel&s inheritance factors, genes, are
carried on chromosomes ! The hromosomal Theory of Inheritance
• It was noted that/
>. uring meiosis, the chromosomes in each cell lined up in pairs, and each
pair of chromosomes was the same size and shape
. 7omologous pairs of chromosomes segregate during meiosis so that each
gamete receives on chromosome from each pair1. After fertilisation, the resulting zygote had a full set of homologous
chromosomes
THE CHEMISTRY O9 CHROMOSOMES AND GENES
THE STRUCTURE O9 DNA
• Each chromosome is made up of about M?3 protein
and K?3 9A Feo$yribonucleic AcidH
• 9A is double-stranded and is made up of a series
of subunits called nucleotides
• *ne nucleotide contains a sugar, a phosphate, and
a base
• The sugar is #nown as deo$yribose
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 39/74
There are K di(erent bases in 9A - Adenine FAH, uanine FH, Thymine FTH
F*r racil FH in 49AH, and ytosine FH
In 9A the bases of each side are %oined together, A can only pair with T, and
can only pair with
If the 9A molecule did not have a twist, it would resemble a ladder, the
sides being the sugar phosphate groups, and the bases being the steps
Information is stored on the seuencing of bases along the 9A molecule,
and a gene is a particular set of bases
i(erent genes have di(erent seuences and are of di(erent lengths along a
chromosome
9ORMATION O9 GAMETES
• In meiosis, haploid gametes are formed, which contain half the normal
FdiploidH number of chromosomes as the chromosome pair separate• uring meiosis, chromosome material is e$changed between chromosomes in
a process called crossing over
• This results in the production of completely uniue gametes
VARIATION AS A RESULT O9 SE7UAL REPRODUCTION
• All gametes vary genetically due to meiosis
• In se$ual reproduction, two gametes are brought together and in fertilisation,
fuse to form a uniue diploid zygote
• This increases variation within a species because it is sheer chance that
determines which gametes will be involved, and the chance that the sametype of sperm and egg being produced and uniting is almost zero
VARIATIONS O9 MENDELS RATIOS
• 0ome characteristics do not display simple dominanceGrecessivness, this is
#nown as co-dominance or incomplete dominance
• These characteristics have two alleles which are @*T7 e$pressed whenever
present
• This means that there are three possible genotypes and three possible
phenotypes
• An e$ample are snapdragons, which have red and white alleles FTheir
possibilities are/ "hite "", 4ed 44, or )in# 4"H
• The phenotype of a co-dominant, heterozygous organism is a blend of the
two co-dominant alleles, Feg. Tall 0hort R 8ediumH
• The ratios of o(spring crosses therefore do 9*T conform with 8endel&s ratios
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 40/74
SE7 LIN;AGE
• 0e$ FgenderH is a genetically determined characteristic
• 7umans have KM chromosomes, two of which, are se$ chromosomes
• In females, both are 6 chromosomes F66H, in males, there is one 6 and one :
chromosome F6:H• 8ales receive their 6 chromosome from their mother, and their :
chromosome from their father, which can carry very few genes
• 6 chromosomes carry a wide variety of genes and it is the genes on the 6
chromosome only which e(ect characteristics FphenotypeH
• "ith this in mind, males therefore are much more li#ely to e$press a
recessive trait as they only have one 6 chromosome on which the
characteristic can be e$pressed
ENVIRONMENTAL E99ECTS
•
The environment includes all the surrounding forces which act on anorganism or its cells
• The e$pression of a gene, as well of the phenotype of an individual, can be
a(ected by the environment
• This can be shown in twins, as although they are genetically identical, due to
growing up in di(erent environments, they are not identical organisms
• Environmental factors can include nutrition, health, and the physical
environment around the organism
.> THE MECHANISM O9 INHERITANCE
DNA REPLICATION
• A replica is a copy of something, and during mitosis chromosomes are
replicated
• 9A replication begins with the separation of its two strands, the bonds
holding them together brea#ing and the strands <unzip=
• @inding proteins prevent the strands from re-attaching as a complimentary
copy of each strand is constructed from new sugar-phosphate-base units
DNA AND THE PRODUCTION O9 POLYPEPTIDES
• 9A is the genetic, or inheritable, material in cells
• It can be replicated and the information it carries can be passed on to new
cells
• This genetic information is organised into units #nown as genes, certain
seuences of bases along a 9A strand
• Each gene contains coded information reuired to ma#e polypeptides
• "hilst 9A does not directly ma#e proteins for the cell, through transcription
and translation it provides the information for the cell to synthesise them
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 41/74
THE GENETIC CODE
• To manufacture a protein, information is reuired about the number, type,
and seuence of amino acids that ma#e up a protein molecule
• This information can be found in a code on the 9A strand
•
The genetic code therefore, is the seuence of bases along the 9A strand• A set of three bases is #nown as a codon and this codon is the code for one
amino acid
• There are in total M> codons which specify one of the ? amino acids
PROTEIN SYNTHESIS
• )roduction of a protein involves/
>. 9A ! A gene on the 9A strand provides the information reuired to ma#e
the polypeptide. 8essenger 49A Fm49AH ! arries information from the 9A Fin the nucleusH
to the ribosomes in the cytoplasm Fas 9A cannot e$it the nucleusH1. Transfer 49A Ft49AH ! @rings amino acids to the ribosomes so they may be
able to be lin#ed together to build the polypeptide chain. Each t49A contains
an anti-codon which contains complementary bases to those found on the
m49AK. 4ibosomes ! Acts as a site for polypeptide synthesis in the cytoplasm as the
lin#ing of amino acids into a polypeptide
chain occurs2. Enzymes ! Involved in catalysing the
reactions
STAGES O9 PROTEIN SYNTHESIS
TRANSCRIPTION
• The double 9A strand in the nucleus unwinds to form two strands with
revealed bases• 49A then moves along one strand, lin#ing complementary 49A nucleotides
together to form a m49A strand F9@. There is a speci'c codon for the
beginning and end of the strandH
• After the entire gene is copied, the m49A moves from the nucleus to the
cytoplasm
ACTIVATION O9 AMINO ACIDS
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 42/74
• In the cytoplasm, an enzyme attaches amino acids to speci'c t49A molecules
TRANSLATION
• The m49A strand binds to a ribosome in the cytoplasm at the end of the
strand which e$presses the <0tart= codon FAH
• A t49A codon on the t49A strand carrying amino acids also binds to the
<0tart= codon within the ribosome
• The ne$t codon on the t49A strand is bound to the ne$t on the m49A strand
and the amino acid is holds is bound, via peptide bond, to the 'rst amino acid
• The 'rst t49A codon is then released from the ribosome, and the ribosome
continues along each strand, continuing this process to form a polypeptide
chain Fa chain of bounded amino acidsH
• *nce the <0top= codon on the m49A is reached, the polypeptide chain is
released into the cytoplasm
• The chain then undergoes speci'c twisting, folding, and shape changing to
eventually form a protein
MUTATIONS
• ariation arises in se$ually reproducing organisms by the recombination and
crossing over of chromosomes in meiosis, and the fusion of two haploid sets
of chromosomes in fertilisation
• 8utation is an alternative to this, which can lead to new alleles in an
organism as changed occur in the 9A on a chromosome
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 43/74
• 8utation however, is often lethal, causing the mutated cells to die
• It is only when the mutated form survives that it can increase the variation of
a population
RADIATION
• uring the ?th entury, #nowledge of the mutagenic nature of radiation Feg.
, nuclearH became much more abundant
UV RADIATION
• ltraviolet radiation from sunlight is common mutagen, which can result in
the bases in a 9A strand to be lost, or cause Thymine bases in the same
strand o lin# together, ultimately preventing 9A replication from occurring
normally
• radiation is also #nown to be a ma%or cause of s#in cancers, and due tothe increasing depletion of the ozone layer, the rate of mutations is li#ely
to rise
IONISING RADIATION
• 4adiation from radioactive materials and $-rays is mutagenic
• These radiations can brea# 9A strands of even whole chromosomes,
resulting in mutation or cell death, depending on the amount of damage
• 0urvivors of ionic radiation, such as those from the 7iroshima bombings and
the hernobyl disaster still e$hibit signs of the radiation&s e(ect today
• The victims have been shown to su(er immediate damage to the 9A in theircells, as well as damage which fully surfaced years later
BEADLE AND TATUM = ONE GENE: ONE POLYPEPTIDE
In >BK>, @eadle and Tatum published results from an e$periment which
involved the radiation of bread mould to inhibit a gene
The results recorded provided evidence of a lin# between genes and proteins
Fwhich are built from polypeptidesH
They used $-rays to cause mutations in millions of strains of the mould which
caused the strain to lac# the ability to produce one of the essential nutrients
for normal growth They determined that this inability was caused by the absence of a necessary
enzyme
@y growing di(erent strains with di(erent combinations of nutrients, they
were able to establish which enzyme was lac#ing in each mutant strain, and
determined that each genetic mutation was at a speci'c site on the mould&s
chromosomes
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 44/74
They concluded that di(erent sites on the chromosomes were associated with
a certain enzyme, leading to the <*ne gene, one polypeptide= hypothesis
DAR6IN REVISITED
• arwin&s theory of evolution by natural selection can be e$plained and
e$panded upon by the genetic information we now have, as we now #now
that variation stems from/>. The random fusion of gametes in se$ual reproduction. rossing over of homologous chromosomes during meiosis1. 4andom assortment of chromosome pairs in meiosisK. 8utations of chromosomes and genes
• enetic variation is e$pressed in the phenotype of an organism
• 0ome phenotypes, the more favorable ones, will survive and reproduce better
than the others
• *ver time, natural selection will operate to change the proportions of certain
genes in a population
NATURAL SELECTION VERSES PUNCTUATED EQUILIBRIUM
• arwin&s theory of 9atural 0election proposes that populations change
gradually over time
• To support this theory, we should see a long seuence of gradual changes to
an organism&s anatomy in the fossil record ! this is usually not the case
• This has been e$plained by supporters of the theory of 9atural 0election by
the rare nature of fossilization occurring, coupled with the rare nature of
'nding a fossilized organism
• @ecause of this rare nature, it seems as though new species suddenly appear,
show little change throughout their life, and then become e$tinct
• It Is the theory of )unctuated Euilibrium that proposes that rather than a
gradual change in an organism, as arwin suggests. Evolution occurs rapidly,
followed by a long period of stability, or euilibrium
.? REPRODUCTIVE TECHNOLOGIES AND GENETIC ENGINEERING
MANIPULATING THE GENE POOL
Ever since humans began taming animals and farming crops they have been
controlling the breeding of the organisms in their care
@y doing this, humans have been able to improve the characteristics of these
organisms for human use and purposes Feg. Darger cattle, faster growing
cropsH
0elective @reeding means deliberately crossing individuals of the same
species with desired characteristics, causing the o(spring to also possess
these characteristics
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 45/74
*ver generations, the preferred characteristics will become the ma%ority due
to the changes that have been made to the genetic composition of a
population
This can be seen as a controlled version of arwin&s Theory of 9atural
0election
ARTI9ICIAL INSEMINATION AND POLLINATION
• Arti'cial insemination is the in%ection of male semen into a female, and is
used commonly by animal breeders for larger animals such as cows, sheep,
and horses
• enerally, the sperm collected is from a male with favourable characteristics
• *nce collected, the sperm can then be transported and used to inseminate
females over a much wider area than by normal mating
• )lants can be arti'cially pollinated by brushing fertile stigmas with pollen
from plants, again with desired characteristics
• These techniues lead to uic#, widespread genetic changes within a speciespopulation
CLONING
• loning is the process of producing genetically identical organisms
• loning occurs naturally in ase$ual reproduction, a clone being is collection of
genetically identical copies
• The cloning of plants has been used for many years, however only recently
have scientists been able to clone a domestic animal, a sheep, olly, being
successfully cloned in >BBC by a techniue #nown as nuclear transfer
technology• uring her life, olly was able to give birth to K healthy lambs, indicating
correct functioning of the cloned cells and genes
• 0ince >BBC, scientists have been able to, albeit with low success rates, clone
such animals as mice, goats, pigs, cattle, and horses
GENETIC ENGINEERING
@iotechnology is the use of various techniues to change organisms at a
molecular level
This permanently alters the genetic blueprint of an organism, as desirable
genes from one organism are isolated, and then inserted into anotherorganism
PRODUCTION O9 A TRANSGENIC SPECIES
• enetically modi'ed organisms are those which have had their genetic
ma#eup deliberately modi'ed by either selective breeding, mutation, or
genetic engineering
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 46/74
• A transgenic species is one which contains a new piece of 9A spliced into a
chromosome in each of its cells
• This new piece of 9A usually allows the organism to produce a protein which
it would otherwise be unable to produce
• The inserted 9A may come from either an entirely di(erent species, or a
di(erent organism within the same species• The production of a transgenic species involves several steps
>. A useful gene and the chromosome it is on is identi'ed. The gene is isolated, or cut-out& of the 9A strand1. In some instances, multiple copies of the gene may be made
Fthrough insertion into uic#ly-reproducing bacteriaHK. The gene is inserted into the cell of another organism, sometimes
with the aid of a vector. The method of insertion is reliant on the
cell
• *nce the gene is inserted, it needs to become part of the genetic material of
that organism, and must be able to be e$pressed
• The organism is not counted as a transgenic organism unless it is able topass on this trait to its o(spring
• Transgenic species have been developed to improve agricultural crops, such
as pest-resistant wheat and cotton
• Divestoc# has also been modi'ed to be resistant to disease or to improve
their meat uality
ETHICS AND TRANSGENIC SPECIES
• 8any social, economic, and ethical issues arise from genetic modi'cation,
especially regarding areas such as/
• 5ood safety and health, environmental protection, regulating issues, socialand economic e(ects, and ethical and moral issues
POTENTIAL IMPACTS ON GENETIC DIVERSITY
• An issue that stems from the use of reproductive technologies is the loss of
genetic diversity which it poses
• If more genetically modi'ed plants and livestoc# are used, local varieties will
lose value on a global scale
• Dess diversity also results in less resilience in a species, following on from
arwin&s ideas of natural selection ! if a change in the environment occurs,
all of the species will su(er due to being genetically identical
E7AMPLE: BT COTTON
• @ascillus thuringiensis is a bacterium that naturally produced chemicals
which #ill insects
• It is used e$tensively in transgenic crops, allowing the crops to defend
themselves against insect predators
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 47/74
• 7owever, if these @t crops become standard throughout the world, other
varieties will be lost, and the crop itself will become more vulnerable due to a
lac# of diversity if the environmental conditions change
• Although these reproductive technologies can be e$tremely bene'cial for the
health and prosperity of crops and livestoc#, we must ta#e into account the
negative conseuences, that is a much thinner range of genetic diversity,which will result from widespread use of these technologies
CHAPTER : THE SEARCH 9OR BETTER HEALTH
.1 6HAT IS A HEALTHY ORGANISM
DE9INING HEALTH AND DISEASE
• e'ning health& is not easy as it has many components, some sub%ective
• e'ning disease& has a similar problem, as it is sub%ective, depending on an
individual&s normal level of functioning
• The "7*&s de'nition of health is/ <a state of complete physical, mental and
social well-being and not merely the absence of disease or in'rmity=
THE MAINTENANCE O9 HEALTH
MITOSIS AND GENES
• The maintenance of health of an organism is assisted by the maintenance
and repair of the body&s cells and tissues
• The function of genes is to ensure all cellular processes are able to continue
• 8itosis allows organisms to grow and to produce genetically identical, correct
cells for repair• ell i(erentiation ! the process by which a less specialised cell becomes
more specialised
• hanges or mutations in the genetic material may occur during the life of an
organism, which can be damaging to healthy cells
• 7ealthy cells have their cell cycle carefully regulated, brought on by the
proteins produced by di(erent types of genes
• "hen tumour suppressor genes mutate, they lose their ability to control cell
division
• The rate of cell division increases and causes a tumour
• i(erent types of cells become specialised for di(erent functions within a
multicellular organism ! ell 0pecialisation
.5 THE IMPORTANCE O9 CLEANLINESS
IN9ECTIOUS AND NON4IN9ECTOUS DISEASE
• isease may come from the organism itself, or from an outside source, such
as another organism or environmental factors
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 48/74
• iseases can be classi'ed as infectious Fable to be caught&H or non-infectious
• Infectious diseases are caused by a pathogen, an infecting organism
• A non-infectious disease is caused by hereditary, lifestyle, or environmental
factors
• )athogens can be/ prions, viruses, bacteria, protozoans, or fungi Fe$plained
further onH
CONTRIBUTING 9ACTORS
• Three interacting factors contribute to health and disease/ the host organism,
the agent of disease, the environment
• The 7ost ! *rganism resistance to infection varies, individuals vary, and the
resistance of a particular individual can vary over time. A healthy person
might resist an infection which is devastating to another, people under stress
may succumb more easily to infections, a person&s resistance may be
stronger than another&s, and a person&s lifestyle may di(er to another&s
• The Agent ! 8ost infective agents only a(ect one species, for e$ample catin+uenza is not passed to humans. The dose of infection may also be too
small to have a signi'cant e(ect, or the e(ect on the host may be varied due
to the body&s reaction to the pathogen
• Environment ! The nature of the environment will a(ect the li#elihood of a
pathogen growing and being passed from on host to another. 8any infectious
agents are spread in crowded, unhygienic conditions
CLEANLINESS AND CONTAMINATION
• eneral hygiene and cleanliness are important in reducing the transmission
of infectious diseases• This can include personal hygiene such as hand washing, or societal hygiene
such as sewage and handling of food
• The provision of clean water and disposal of waste water or sewage is a
public health issue, water supplied to houses must be safe to drin#
PATHOGENS
• "hen an organism causes disease, they are called a pathogen
• To cause disease, organisms reuire the right conditions to multiply and be
transmitted
HO6 DISEASES ARE SPREAD
• Airborne ! ust and droplets in the air may carry microorganisms
• ontact ! ontagious or infectious diseases can be caught by direct or
indirect contact
• @y other *rganisms ! *rganisms #nown as vectors may transmit diseases,
eg. 8osuito
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 49/74
.< THE SEARCH 9OR MICROBES AS CAUSES O9 DISEASE
PLAGUES AND EPIDEMICS
MICROBES AS THE CAUSE O9 IN9ECTIOUS DISEASE
• ntil the mid->Bth entury, people thought that living things came intoe$istence from non-living matter, spontaneous generation
• Two scientists who contributed most to the understanding of causes of
diseases were Douis )asteur, and 4obert Noch
LOUIS PASTEUR
• iscovered that most infectious diseases are caused by microorganisms, or
germs
• This became #nown as the germ theory of disease
• 7is demonstration, via the swan-nec#ed +as# e$periment, proved that living
micro-organisms are present in the air, destroying the theory of spontaneousgeneration
• 7e also discovered the techniue of )asteurisation, heating a liuid to 22 to
destroy any microbes present
• 7e also demonstrated the 'rst idea of vaccination, infecting 2 sheep with a
small dose of @acillus anthracis, and then 2? sheep, including the original 2
with a large dose
• Those who were administered the small dose and then the large dose
survived, whilst those administered only the large dose died
ROBERT ;OCH
• 0ucceeded in isolating the bacterium which causes the disease from the
blood of dying animals
• 7e found that healthy animals in%ected with the blood of diseased animals
became diseased
• To prove that a bacterium cause a certain disease, he isolated it and in%ected
an animal with only the isolated bacterium
• Noch&s )ostulates describe the criteria which must be met if we are to be sure
a particular micro-organism causes a disease
MALARIA
• aused by the protozoan parasites of the genus )lasmodium, transmitted by
the female Anopheles mosuito
• 5irst identi'ed by 4onald 4oss
• espite many programs to eradicate it, malaria remains a ma%or health
problem in tropical and sub-tropical areas
AGENTS O9 DISEASE
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 50/74
• An infectious disease is one that is caused by a pathogen and can be passed
on from one organism to another. These pathogens include/
PRIONS
• Infectious agents that cause brain disease in mammals
• They are proteins that have been altered to an abnormal shape
• iseases caused by prions include 8ad ow isease in cattle, and
reutzfeldt-Ua#ob disease in humans
VIRUSES
• ery small, only visible with an electron microscope
• 9o cellular, simply nuclear material F9A or 49AH encased in a protein coat
• iruses in%ect their 9A into another cell and this in%ected cell produces new
viruses which escape to infect others
• There are no cures for viruses, only prevention through vaccination
• iruses include smallpo$, measles, in+uenza, and AI0
BACTERIA
• )rocaryotic cells ! lac#ing of a nucleus or membrane
• @acterial diseases can be treated by antibiotics
• E$amples include tetanus, chlamydia, and Uohne&s disease
PROTOOANS
• 0ingle celled, eu#aryotic Fcells encased in a membraneH organisms
9UNGI
• Eucaryotic organisms, mostly comprised of microscopic tubular 'laments
• E$amples of diseases cause by fungi is tinea or athlete&s foot, and ringworm
MACROPARASITES
• Darge parasites that can be seen with the na#ed eye
• Eg. Dice, mites, tic#s, and +eas in animals and mites and aphids in plants
THE ROLE O9 ANTIBIOTICS
• Antibiotics are substances capable of destroying or inhibiting the growth of
bacteria
• They are chemicals that act on the pathogen without harming the host
• They are only e(ective against bacterial diseases, not viruses
• The 'rst antibiotic was )enicillin
• Antibiotics wor# internally on a cellular level
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 51/74
• @ecause of the widespread use of antibiotics however, some bacteria have
evolved resistant strains, which resist antibiotics
• In response, scientists have had to develop stronger antibiotics, however
problems may arise if the bacteria grows resistant to this stronger treatment
.> PROTECTING THE BODY: DE9ENCE BARRIERS
• The body has various defence mechanisms against pathogens
• 5irstly ! )rotecting the body at possible entry points, non-speci'c protection
which aim to prevent pathogens from entering the body
• 0econdly ! efence mechanisms operate when pathogens succeed in
entering the body, also non-speci'c response
• Thirdly ! 0peci'c defence mediated by lymphocytes
DE9ENCE BARRIERS = PREVENTING ENTRY
THE S;IN BARRIER
• 8icroorganisms cannot penetrate the s#in unless it is bro#en
• If the s#in brea#s, the blood clotting mechanism uic#ly forms a seal to
prevent entry of pathogens
MUCOUS MEMBRANES
• Dine the digestive, respiratory, reproductive, and urinary tracts with a thic#,
slimy mucous
• This mucous protects against invasion , aided by the presence of an antibody
in it which reacts to potential pathogens
SPECI9IC RESPONSES = THE IMMUNE RESPONSE
• The body&s immune response is its reaction to invasion by foreign materials
• These include viruses, bacteria, and to$ins
• The body identi'es these substances as foreign and triggers a response to
attempt to destroy them
• The substances which trigger this reaction are #nown as antigens
• This response can pose problems in organ transplants as the host&s body
identi'es the transplant as foreign, and attempts to attac# and destroy the
new tissue
DE9ENCE ADAPTATIONS = NON4SPECI9IC RESPONSES
IN9LAMMATION RESPONSE
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 52/74
• "hen any body tissue is damaged, the area becomes red, hot, swollen, and
painful
• @lood circulation to this area is increased and the blood vessels dilate and
become lea#y
• This response helps to con'ne the pathogen to one area of the body whilst
the body increases production of "hite @lood ells to destroy it• The chemicals histamine and prostaglandins are related to this response
PHAGOCYTOSIS
• )hagocytes are white blood cells which can actively move from the blood to
tissues, where they ingest and destroy any foreign material Fcontaining
foreign antigensH, including pathogens
• This action is #nown as phagocytosis
SEALING O99 THE PATHOGEN
• "hen the body is unable to neutralise an antigen, chronic in+ammation
involving macrophages FphagocytesH and lymphocytes Fproduced in the
lymph nodesH may occur
• The reaction forms a cluster of cells which surround the area of infection
.? THE IMMUNE RESPONSE
• "hen we are e$posed to an antigen for the 'rst time, our body responds by
producing lymphocytes
• Dymphocytes are a type of white blood cell, the two main types being T-ells
and @-ells
• Antibodies are produced by the @-ells in the lymph nodes in response to a
speci'c antigen entering the body
• Antibodies are proteins that bind to antigens, forming the antigen-antibody
comple$ which activates the production of proteins that results in the
ingestion and destruction of bacteria
T4CELLS
• There are four types of T-ells/ 7elpers Fstart immune responseH, ytoto$ic
Fattac# infected cellsH, 0uppressors Fsupresses immune responseH, and
8emory Faids pathogen immunityH
• T-ells form in the bone marrow, and mature and develop in the thymus
gland
• They remain inactive in blood until they come in contact with and antigen,
which binds onto the T-ell, activating it to multiply
• T ells control the cell-mediated response, in which various T ells destroy
the antigen or foreign cell
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 53/74
• *ther T ells stimulate the activity of @-ells and phagocytes, whilst some
remain in the body as T 8emory ells, which aid in the uic# removal of a
previously encountered antigen
THE ACQUIRED IMMUNE RESPONSE
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 54/74
• ytoto$ic T-ells destroy the cells which carry foreign antigens
• 7elper T-ells secrete chemicals which regulate cytoto$ic T-ell and @-ell
functions
• 0uppressor T-ells regulate @ and T ells, suppressing the immune response
once the pathogen has been destroyed
• 8emory T-ells recognise an antigen when it reappears and have the 7elpersuic#ly produce a large amount of antibodies
B4CELLS
• 8ature and develop in the bone marrow
• They control the blood response in which @ ells present in the blood and
lymph nodes are activated by the presence of antigens
• Activated @ ells clone themselves and then di(erentiate into either plasma
cells, which send antibodies to the blood, or memory cells
IMMUNITY AND IMMUNISATION PROGRAMS
• *nce a pathogen had infected the body and then been destroyed by it, the
infected person is said to be immune to that disease
• This immunity can be short-lived, or life-long
VACCINATION
• accination, or immunisation, is the process of ma#ing people resistant toinfections cause by pathogens
• It involves the administering of an in%ection or oral dose of vaccine
• accines are preparations of wea#ened or dead infective microorganisms that
are in%ected into the body to provo#e the immune response without causing
any symptoms
• 0ome vaccines wor# for life, whilst some much be readministered
)at 4ussell ! 0t 5rancis 6avier ollege
)rimary infection
compared to secondary
infection after 8emory
ells have been created
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 55/74
• Active immunisation involves the in%ection of an antigen in the form of a
vaccine, which stimulates the @ and T 8emory ells speci'c to that antigen
• )assive immunisation involves the in%ection of antibodies that another
organism has produced in response to infection by a particular pathogen ! it
does not provide long term protection, however it is immediate
DELIBERATE SUPPRESSION O9 THE IMMUNE SYSTEM
• 0uppression of the immune system is necessary for the process of organ
transplants
• @ecause blood drains from the transplanted organ into the new host body,
the body recognises the cells as foreign and begins the immune response,
e(ectively attac#ing the new organ, aiming to destroy the tissue
• 4e%ection is reduced by matching transplanted tissue proteins to the
recipient&s proteins and by giving drugs to suppress the immune response
. EPIDEMIOLOGICAL STUDIES
6HAT IS EPIDEMIOLOGY
• Epidemiology is the study of diseases that a(ect many people, it describes
the patterns and cause of diseases in populations
• iseases studied include infectious diseases and those related to peoples&
life-style and environment
• They establish lin#s between lifestyle and disease eg. 0mo#ing and lung
cancer
• 8odern methods of epidemiological studies involve large groups of people to
collect a large, diverse uantity of information to be statistically analysed
• There are three broad categories of epidemiological studies/
• escriptive studies ! 0how patterns in the way diseases happen to be
distributed in populations
• Analytic studies ! )lanned investigations to test a speci'c hypothesis
• Intervention studies ! 8easure the e(ectiveness and safety of certain
interventions
LUNG CANCER
• aused by the abnormal growth of cells in the lung
• In 90" ??>, lung cancer was the most common cause of cancer deaths in in
people aged 2?-PK
• Epidemiological studies concluded that smo#ing is a ma%or cause of lung
cancer
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 56/74
• 5actors ta#en into consideration were the time one has been smo#ing,
cigarettes smo#ed each day, as well as other factors such as age, gender,
and year
CAUSES O9 NON4IN9ECTIOUS DISEASES
• 9ot caused by pathogens
• Include inherited diseases, nutritional de'ciencies, and environmental
diseases
INHERITED DISEASES
• Include gene and chromosome abnormalities and are genetically inherited
• They include minor disorders such a colour blindness, or ma%or disorders such
a cystic 'brosis
• They can be successfully treated by such things as surgery, drug treatment,
of special diets
• 7owever faulty genes cannot be corrected
NUTRITIONAL DISEASES
• Dac# of a vital component of diet. Eg. Dow vitamin can lead to 0curvy
CASE STUDY: SCURVY
• aused by a lac# of vitamin in the diet
• "as very prevalent in the time of sea e$ploration, where perishable food
items could not be ta#en
• It caused the capillaries to become fragile and bleed within the tissues, thegums to become swollen and rotten, teeth to fall out, wounds fail to heal, and
if untreated, death
ENVIRONMENTAL DISEASE
• an include e$posure to radiation, heavy metals, pollution in the air, soil or
water, lifestyle, loud noise, stress, and drug abuse
. STRATEGIES TO PREVENT AND CONTROL DISEASE
• There is a wide range of strategies to prevent and control disease in humans
PUBLIC HEALTH PROGRAMS
• 7elp to control and prevent disease by strategies directed at three targets;
the pathogen, the host, and the environment
• There is an increasing emphasis on )4EE9TI9 disease rather than
T4EATI9 it
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 57/74
• Daws reuiring government authorities to be noti'ed of the occurrence of
certain diseases has helped stop the spread of disease, reuiring people
e$hibiting the disease to be uarantined
• )eople are protected by improved awareness from public education
campaigns that in+uence people to improve their health. Eg. <Vuit= campaign
• accination programs and screening programs are also used to help preventdisease
QUARANTINE AS A CONTROL MEASURE
• Vuarantine is a period of isolation to prevent the spread of a contagious
disease
• Australia in particular has strict uarantine laws to protect the uniue plants
and animals from introduced species and disease
• Vuarantine inspectors patrol the entry of ships and aircrafts into Australia to
ensure the preventing of foreign disease entering the country
• Imported animals face a time in isolation and imported plants are e$amine toensure they bring no harmful substances
PESTICIDES
• hemicals that can destroy organisms that directly damage crops or plants,
or cause disease in livestoc# and animals
• They are also used to eliminate vectors eg. )otato leaf roll virus caused by
Aphids
• )esticides are often essential for the eLcient production of a healthy
agricultural crop, but their use may also cause environmental problems, such
as accumulation of pesticides in the food chain, and destruction of organismsother than those intended
• An e$ample is T, which used to be used as a common pesticide
• T does not brea# down easily, and stays in the environment for a long
period of time, poisoning soils and being carried around the world in water.
• T can have varying negative e(ects on organisms, for e$ample ma#ing the
shells of some bird eggs softer and more vulnerable
GENETIC ENGINEERING
• enetic engineering has produced disease-resistant plants and animals
• These plants and livestoc# have their genes altered to ma#e them resistant tocommon pests and diseases
• 7owever, genetic engineering remains a controversial topic
IMPLICATIONS 9OR THE 9UTURE
• The prevention and control of disease is a continuing battle
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 58/74
• In some areas, there has been immense success, such as the eradication of
smallpo$ and the decline of once-common human diseases through
vaccination programs
• 0ome controls wor# well for a time but then their e(ectiveness declines
• The development of drug resistance in pathogens means that without
continued research for new chemicals to destroy them, pathogens willcontinue to spread disease
OPTION 5: GENETICS: THE CODE BRO;EN
5.1 THE GENETIC CODE
DNA
9A Feo$yribonucleic AcidH is a double-stranded, helical molecule made up
of repeating units called nucleotides. FEach nucleotide contains a sugar,
phosphate, and a baseH
9A is able to replicate itself, so copies of a certain 9A molecule can be
made
enes are the particular seuences of bases along a 9A molecule
The information to create a new organism is transmitted by these genes
9A is present in almost every cell in an organism, contained mostly in the
nucleus
THE DNA CODE
The structure of 9A provides a code containing the information reuired to
produce a polypeptide
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 59/74
This 9A code is stored in the seuence of bases FA, T, , H in the 9A
strands
These bases code for amino acids, which form a chain to ma#e up
polypeptides
In humans, there are ? of these amino acids, and each is coded by a triplet
of bases called a codon The code determines/
>. "hich amino acids are put into the polypeptide. 7ow many amino acids in the polypeptide1. The arrangement of amino acids in the polypeptide
• 9ot all of the 9A functions as a code, the amount of genetic material in cells
greatly e$ceeds the amount of coded information used
• *nly some of this non-coding 9A is essential, the rest being regarded as
redundant& or %un#& 9A, however it may serve uses we do not yet #now
POLYPEPTIDE SYNTHESIS
• A gene is a region of 9A which controls inherited characteristics through
controlling polypeptide synthesis Fwhich fold to become proteinsH
• It does this by transferring coded information FbasesH to m49A, determining
the amino acids to be added in a polypeptide
• )olypeptide synthesis involves the following processes/
M. 9A ! A gene on the 9A strand provides the information reuired to ma#e
the polypeptideC. 8essenger 49A Fm49AH ! arries information from the 9A Fin the nucleusH
to the ribosomes in the cytoplasm Fas 9A cannot e$it the nucleusHP. Transfer 49A Ft49AH ! @rings amino acids to the ribosomes so they may be
able to be lin#ed together to build the polypeptide chain. Each t49A contains
an anti-codon which contains complementary bases to those found on the
m49AB. 4ibosomes ! Acts as a site for polypeptide synthesis in the cytoplasm as the
lin#ing of amino acids into a polypeptide
chain occurs>?.Enzymes ! Involved in catalysing the
reactions
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 60/74
STAGES O9 PROTEIN SYNTHESIS
TRANSCRIPTION
• The double 9A strand in the nucleus unwinds to form two strands with
revealed bases
• 49A then moves along one strand, lin#ing complementary 49A nucleotides
together to form a m49A strand F9@. There is a speci'c codon for the
beginning and end of the strandH
• After the entire gene is copied, the m49A moves from the nucleus to the
cytoplasm
ACTIVATION O9 AMINO ACIDS
• In the cytoplasm, an enzyme attaches amino acids to speci'c t49A molecules
TRANSLATION
• The m49A strand binds to a ribosome in the cytoplasm at the end of the
strand which e$presses the <0tart= codon FAH
• A t49A codon on the t49A strand carrying amino acids also binds to the
<0tart= codon within the ribosome
• The ne$t codon on the t49A strand is bound to the ne$t on the m49A strand
and the amino acid is holds is bound, via peptide bond, to the 'rst amino acid
• The 'rst t49A codon is then released from the ribosome, and the ribosome
continues along each strand, continuing this process to form a polypeptide
chain Fa chain of bounded amino acidsH
• *nce the <0top= codon on the m49A is reached, the polypeptide chain is
released into the cytoplasm
• The chain then undergoes speci'c twisting, folding, and shape changing to
eventually form a protein
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 61/74
GENE E7PRESSION
• A gene undergoing these processes is said to be being <e$pressed=, the code
being used to ma#e a polypeptide
• "e can see this gene e$pression in the phenotype of a cell or organism, that
is, the observable, physical features
5.5 VARIABILITY 6ITHIN A TRAIT
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 62/74
MULTIPLE ALLELES
i(erent forms of a gene that in+uences one characteristic are called alleles
Each individual can have two alleles for a particular gene, one on each
homologous chromosome
"hen more than two alleles in+uence one trait, they are called multiplealleles
In this case, one allele is normally dominant to a series of recessive alleles,
each with varying degrees of dominance over the others
An e$ample of this is in rabbits, whose coat colour is controlled by K di(erent
alleles
They show the following seuence of dominance/ Ag S h S 7i S Al
THE INHERITANCE O9 BLOOD GROUPS IN HUMANS
• In humans, there are several blood groups under which blood can be
identi'ed• This is determined by the A@* and 4hesus systems
• These systems are important as during blood transfusions, an incorrect blood
group could be fatal, due to a reaction similar to the antigen-antibody
reaction
ABO GROUPS
• In the A@* system, there are four blood groups/ A, @, A@, and *
• There are three alleles for this system/ A, @, and *
• A and @ are completely dominant over *, however are co-dominant to each
other, put simply,A R @ S *
• This means that people of the blood group A can have the genotype AA or
A*, whereas people of the blood group * can only have the genotype **
THE RHESUS BLOOD GROUP
• The second system of blood grouping is based on the rhesus factor, and is
represented by a <= or a <-< following the A@* group
• The rhesus For 4hH factor is coded by two alleles, and so relies of simple
ominantG4ecessive inheritance, the <= allele being dominant to the <-<
allele
POLYGENIC INHERITANCE
• In many cases, a trait FphenotypeH is not e$pressed by only one gene, but a
combination of many genes, or polygenes, located on di(erent chromosomes
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 63/74
• )olygenic inheritance is especially noticeable in height in humans, with
overall height being a(ected by many di(erent characteristics F7eight of/
nec#, body, head, legs etcH
DNA 9INGERPRINTING
• All organisms produced by natural se$ual reproduction have uniue 9A
• Although it is the coding regions of 9A Fthe e$onsH which ma#e up an
organism, it is the non-coding regions Fthe intronsH that are able to be used to
uniuely genetically identify an individual ! This is #nown as 9A
5ingerprinting
• 4ecombinant 9A technology allows the 9A of an organism to be analysed
and compared with other 9A samples
• 9A 'ngerprinting can be used in medicine, genetics research, and forensic
science
5.< INHERITANCE O9 GENES
MEIOSIS
• The traits of o(spring re+ect the inheritance of genes from the parents
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 64/74
• 8eiosis is a type of cell division which occurs during se$ual reproduction,
resulting in the splitting of a somatic FdiploidH cell into two haploid cells
• Three di(erent outcomes occur as a result of meiosis/a. enes on di(erent chromosomes are inherited according to 8endel&s
laws
b. enes on the same chromosomes are inherited together, their traitsusually occurring together. This is #nown as DI9NE
c. enes on chromosomes that cross over create new combinations of
traits in the o(spring
DIHYBRID CROSSES
• 8endel also carried out e$periments involving two characteristics, #nown as
dihybrid crosses
• 5or e$ample, crossing reen 4ound peas with :ellow "rin#led peas FTwo traits
being crossedH
•
"hen heterozygous organisms are crossed, they give a ratio of B/1/1/>
• FThis is a heterozygous cross ! g4r -S 4, r, g4, grH
MENDELS LA6S
8endel studied the inheritance of genes on di(erent chromosomes using
monohybrid crosses
7e summarized his 'ndings into two laws/
The Daw of 0egregation/ The alleles of a gene pair separate at gamete
formation so that each gamete contains only one allele of each gene pair
The Daw of Independent Assortment/ Each gene pair sorts out independently
of other gene pairs at gamete formation ! meaning that either allele of a
gene pair can combine with either allele of another gene pair
LIN;ED GENES
• The genes on any given chromosome are usually inherited together and
therefore said to be lin#ed
• If genes for colour and shape, for e$ample, were on the same chromosome,
they would not separate independently, and would pass directly into the
gametes together
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 65/74
• 7owever lin#ed genes can be separated from each other in meiosis if crossing
over occurs, the further apart they are on the chromosome, the more li#ely
they will separate
CHROMOSOME MAPPING
• hromosome mapping gives us a picture of the arrangement of an
organism&s genes on its chromosomes
• If genes are close together on a chromosome, they usually stay together
during meiosis
• 0tudying the freuency of recombination of traits in breeding e$periments
has allowed scientists to produce maps of the genes on chromosomes
• The formula for estimating the distance between two genes on a
chromosome is/
• These maps provide an insight into genetic lin#age and show the relative
distance between genes
• Today, recombinant 9A technologies can produce more accurate maps
showing the position of genes in term of the seuence and number of bases
involved
RELATIONSHIP BET6EEN SPECIES
•
*rganisms of the same species share a common gene pool and have similarchromosome maps
• The more closely related organisms are, the more genes they have in
common
• The identi'cation of lin#age groups Fgrouped genesH in di(erent organisms is
one method of analyzing these relationships between species
• Evidence of similarities in lin#age groups between species indicates the
possibility that each organism shared a common ancestor
• ltimately, chromosome mapping of gene lin#age provides another source of
evidence for the evolution of living organisms
5.> THE HUMAN GENOME PRO@ECT
• The genome of an organism is all the genetic material of an individual or
species
• In a haploid Fhalf the total amount of chromosomesH, the human genome
consists of about 1 billion 9A bases arranged along the chromosomes
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 66/74
• The 7uman enome )ro%ect F7)H is an international pro%ect which aimed to
identify all the human genes and to determine the seuences of these 1
billion bases in human 9A
• >P countries participated in the 7) Fthis included Australia, The 0A, Uapan,
the E, hina, N, Italy, and 5ranceH
• The pro%ect began in >BB? and aimed to ta#e >2 years to complete, however'nished years early in ??1, achieving the goal of completely identifying
the human genome
• This achievement was made possible largely by rapid advancements in
technology
• A collaborative approach was also ta#en, which allowed the results to be
more uic#ly obtained and wor# together, each participating country being
assigned a particular tas#
• These tas#s included/
>. enetic mapping of the human genome. )hysical mapping of the human genome
1. 9A seuencingK. Analysing the genomes of other organisms
BENE9ITS O9 THE HUMAN GENOME PRO@ECT
• The bene'ts of the 7) will be enormous to advancing our #nowledge and
technology in biology and medicine, as detailed 9A information will be
available in further research
• In medicine, the bene'ts include signi'cantly aiding in diagnosing, treating,
and preventing disease F5or e$ample, insulin bacteriaH
• )eople with family history of a particular disease are also able to 'nd out
whether or not they carry the diseased genes, resulting in faster diagnosis
and uic#er prevention of diseases
• In the future, this may lead to the ability to identify disease-causing genes in
a foetus and splice out the defective alleles
• @iologically, the 7) allows for more detailed comparisons to be made
between species and improved and easier genetic research
LIMITATIONS O9 THE PRO@ECT
• espite providing a signi'cant leap in our understanding of the human
genome, the 7) is loo#ed at as preliminary data, and not a 'nal
understanding of cell and organism functioning
• "hat we do with this preliminary data provides the real challenge, as simply
#nowing the base seuences does not determine the functioning of every
gene
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 67/74
• Ethical, legal, and social implications and issues also arise from the possible
information gathered as a result of the 7)
PRODUCING RECOMBINANT DNA
4ecombinant 9A is produced in cells as a result of chromosome crossing-
over in meiosis
@efore the 7), this could only be achieved through the deliberate crossing
of organisms, however now, recombinant 9A is able to be produced in a lab
using molecular technologies
4estriction enzymes cut pieces of 9A, and are resealed to other pieces of
9A using sealing enzymes to form new recombinant 9A
E7AMPLE: INSULIN
>. The human gene for ma#ing insulin is cut out of the chromosome ta#en from
a human pancreas cell FIslets of Dangerhans cellH using an enzyme called
restriction enzyme.. A ring of 9A called a plasmid is removed from the E.coli bacterium and cut
open with a restriction enzyme.1. The human insulin gene is mi$ed with the cut plasmid. All of the cut ends
FWstic#y endsWH can bond together using the enzyme 9A ligase to ma#e a
new 9A molecule.K. The WnewW plasmid, that contains the recombinant 9A, is inserted bac# into
the bacterial cell.2. "hen the bacterial cell reproduces, so does the plasmid and hence the
human insulin gene. "hen provided with the appropriate nutrients, these
cells produce human insulin which can be e$tracted and used by diabetics.
E7AMPLES O9 RECOMINANT DNA TECHNOLOGIES
• utting and re%oining 9A using restriction enzymes and sealing enzymes
• se of vectors to act as carriers of 9A fragments or genes
• )olymerase chain reactions to produce multiple copies of 9A
• 9A hybridization
• se of genetic probes Fradioactive segments of 49A or 9AH which are
complementary to a 9A seuence being sought
MAPPING GENES USING RECOMBINANT DNA TECHNOLOGY
• 4ecombinant 9A has played a large part in mapping genes on chromosomes
• sing lin#age studies in the >BP?s, scientists were able to construct genetic
maps using genetic mar#ers&, regions of 9A that were either e$ons or
introns Fcoding or non-codingH
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 68/74
• 8ar#ers that usually occurred together were assumed to be determined by
genes on the same chromosome and were said to be lin#ed
• These lin#age maps however, only showed relative positions of the mar#er
regions, and so genetic mapping using new technology enabled the rapid and
accurate advancement of the 7)
• Two such technologies were 4estriction 8apping, and 9A 0euencing
5.? GENE THERAPY
If faulty genes can be replaced, switched o(, or corrected, then diseases can
be treated at its source ! this method of treatment is #nown as gene therapy
ene therapy becomes possible only when the genes responsible for the
harm are identi'ed
It represents a more eLcient way to diagnose, treat, and prevent disease,
however, is still largely e$perimental
In short, gene therapy aims to replace faulty genes with healthy ones
There are several steps the need to be followed to achieve this/o Identi'cation of the disease-causing gene
o Docation of cells or tissues involved in the disease
o Access to multiple copies of the normal gene
o Insertion of the normal gene into the a(ected cells
8ost commonly, viruses are used as vectors to carry the replacement gene to
a cell, the virus being in%ected with the normal gene, and then the human
being in%ected with the virus
"hilst this is the most eLcient way, it also poses ris# as viruses are
commonly pathogens themselves
9on-viral methods, such as direct introduction, nanotechnology, and
constructing arti'cial chromosomes are also being used, however none are ase(ective as the viral method
5. GENETIC CHANGE
• Any permanent change in the 9A is called a mutation
• A mutation therefore, can involve changes in either the chromosome, or a
single gene
CHROMOSOME MUTATIONS
•
0ome mutations involve a change in chromosome number, which arisesthrough an abnormality in meiosis, leaving the person with either too many
or too few chromosomes
• In most cases, this occurs prior to gamete formation, and the gametes
produced do not produce viable o(spring on fertilization
• In own&s 0yndrome, three copies of chromosome > are inherited, resulting
in a total of KC chromosomes in the o(spring, this is #nown as Trisomy
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 69/74
• Another chromosome mutation is )olyploidy, which results in an individual
having whole e$tra sets of chromosomes, possibly resulting from improper
separation in mitosis
• )olyploidy is much more common in plants and often results in larger,
stronger plants
• In animals however, polyploidy is fatal• )arts of a chromosome may also be rearranged and the seuence of 9A
altered, causing visible changed in the chromosome structure
GENE MUTATIONS
8utations may often not be large enough to a(ect chromosome structure, but
can be as small as to a(ect only a single base, or the involve a whole gene
9A seuence
There are two main types of gene mutations, base substitution, and
frameshift mutations
@ase substitution is when a single base may be replaced by another, causinga point mutation which changes codons, and by e$tension, disrupts normal
amino acid production
5or e$ample, AT might change to A. These codons each code for a
di(erent amino acid and so regular bodily functioning is a(ected
espite this, some base substitutions can result in no amino acid change, or
an amino acid change with no visible e(ect to the organism
5rameshift mutation occurs when a single base is added or deleted from a
9A seuence
This loss or addition results in a change in the codon seuence after it has
occurred, thus a(ecting amino acid production and the functioning of
produced proteins
5or e$ample, the seuence T7E 5AT AT ATE T7E 8AT, would change to T7E
55A TA TAT ET7 E8A T, if an e$tra 5 was added after the 'rst codon
• ystic 5ibrosis F5H is a disease caused by gene mutation, most commonly a
base deletion Fframeshift mutationH from chromosome C
• 8utations can occur spontaneously during 9A replication, and the rate can
be increased by environmental factors such as radiation, chemicals, or
viruses
DNA REPAIR AND MAINTENANCE
• hanges that occur to the 9A in a fully di(erentiated specialized cell may
lead to the malfunctioning or death of that cell
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 70/74
• In dividing cells, it is important that 9A is chec#ed and repaired, if
necessary, by 9A repair genes to ensure healthy, somatic cells
• This repair reduces the chance of continuing a possible harmful mutation that
has arose in a cell
@UMPING DNA
• Uumping 9A refers to the idea that some pieces of 9A are transposable,
they can move from one position in the 9A to another
• 8any types e$ist, di(ering in length and behavior, but their movement is not
common
• As well as moving themselves, %umping 9A can rearrange neighboring
segments of 9A due to deletion, addition, or relocation of some bases
• Uumping 9A are li#ely to have played a ma%or role in the evolution of life on
earth, as they/o estabilise the 9A in cells
o eregulate the reading of geneso @ecome active in bursts after periods of inactivity, causing several
characteristics to change at the same time
• Transposable elements F%umping 9AH is thought to be lin#ed so some
genetic diseased such a breast cancer and leu#emia
GERM LINE AND SOMATIC MUTATIONS
• 8utations that arise in an organism&s somatic cells Fbody cellsH a(ect only the
organism in which the mutation occurred. This is common in cancers and is
#nown as somatic mutations
•
erm line mutations however, arise in an organism&s germ cells Fcells thatform sperm or eggsH and so will be passed on to, and a(ect the o(spring,
possibly causing inherited diseases
• A favorable germ line mutation provides the basis for natural selection and
the evolution of a species, however favorable mutations are much more rare
than unfavorable
5. SELECTIVE BREEDING
0elective breeding is the practice of choosing individuals in a population of a
species for mating, to obtain o(spring with certain characteristics
4epetition of this will result in a population in which the ma%ority ofindividuals e$press these desired characteristics
7umans have been controlling the breeding of domestic animals and plants
in this way for thousands of years, particularly today in livestoc# and
agriculture to produce animals and plants as superior food sources
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 71/74
6HEAT BREEDING
• In terms of volume, wheat is the more important agricultural crop in Australia
• The selective breeding of wheat has been practiced in Australia since the
times of the early settlers, as European wheat did not grow e(ectively in
Australian conditions• *ver time, wheat has been bred to have certain characteristics and provide a
ma$imum yield. 0ome of these characteristics are/o 4apid progression through life cycle
o Increased grain yield
o isease resistance, particularly to rust fungi
o Increased tolerance to frost, drought, and acidic soils
o Improved +our uality
• "heat in Australia has changed dramatically from the time of European
settlement, as humans have cross-bred many di(erent species to end up with
a species of wheat best suited to both the environmental conditions and the
needs of the human population• 5or e$ample, in the early >B??s, wheat was cross bred with Indian wheat to
increase rust resistance and shorten ripening time
• 5ederation& "heat is a notable e$ample from the >B?s, being a wheat
cultivar, that is it cannot be found in the wild and has been selectively bred
for speci'c characteristics
GENE CLONING
• A clone is an e$act genetic copy, and 9A, cells, and whole organisms can be
clones
•
ene cloning uses genetic engineering techniues to produce unlimitednumbers of identical copies of genes ! clones
• A number of recombinant 9A technologies may be used in cloning, for
e$ample, genes can be inserted into bacteria, which multiply to produce
more than billions of copies of the inserted gene
• )olymerase hain 4eaction F)4H is the newest and fastest form of gene
cloning
• ene cloning has many practical uses, particularly in research, forensics, and
medicine
6HOLE ORGANISM CLONING
• "hole organism cloning is a method of reproduction that results in
genetically identical o(spring which are e$act genetic copies of the parent
• )lants can be cloned using a tissue culture, cells ta#en from the parent plant
being grown into a whole plant
• Animals however, reuire a nuclear transfer, where the entire genome FKM
chromosomesH from a cell of the parent is inserted into an egg cell that has
had its nucleus removed
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 72/74
• The egg cell is then implanted into a surrogate mother where is develops
normally
• The o(spring that results is a genetically identical copy of the parent animal
5. DEVELOPMENT
EMBRYONIC DEVELOPMENT
GENE CASCADES IN LIMB 9ORMATION
• All animals have at least one cluster of homeotic genes Fgenes that
determine what parts of the body form what body partsH that lay down the
pattern for the front-to-bac# body a$is
• In vertebrates, the development of the body and limbs is always organized
the same way, the body developing from head to tail and limbs from the base
to the tips
EVOLUTIONARY RELATIONSHIP REVEALED BY HOMOLOGY
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 73/74
The evolution of life on Earth over billons of year has produced tremendous
variation in the appearance of living things
7owever, studies in comparative anatomy, such as that of the pentadactyl
limb have revealed similarities between what would otherwise be considered
very di(erent organisms
omparative embryology has shown how di(erences in an initially similarstructure appear as development proceeds
As scientists delve further into comparing the inner wor#ings and
biochemistry of organisms, the common origins of living things is revealed
repeatedly
It has been shown that nucleotide seuences in the genes of di(erent
organisms is e$tremely similar
5or e$ample, the enzyme needed for a particular reaction in the respiration
pathway in bacteria has a similar structure to humans
This similarity provides evidence for evolutionary relationships between these
organisms and so is another point of evidence for evolution, particularly from
a common ancestor
THE EVOLUTION O9 GENES
• urrent research suggests that many gene contain nucleotide seuences that
have changed only slightly and slowly during the evolution of life on Earth
• 5or this reason, they are able to be used to compare relationships and
relatedness between organisms, as they would not have changed much since
their time of creation
• @ecause the homeobo$ seuence Fclosely similar seuences that occur in
various genes and are involved in regulating embryonic developmentH is
similar in 7o$ genes, it is thought that they are homologous genes and all
share a common ancestral gene
• 7o$ genes are also arranged in clusters on chromosomes and can be found in
similar positions within these clusters across the animal #ingdom
• @ecause of this, it seems li#ely that all animal species inherited their 7o$
genes from a common ancestor
• The study of mutations in homeotic genes show that a small mutation can
result in a dramatic and sudden change in an organism as the developmental
cascade is altered
• The study of the evolution of gens, particularly homeotic genes, and the
e$pression of genes, particularly during development, is giving us anunderstanding of their e(ects on living organisms and providing new
information about evolutionary relationships
)at 4ussell ! 0t 5rancis 6avier ollege
7/23/2019 2014 Biology Notes
http://slidepdf.com/reader/full/2014-biology-notes 74/74
END O9 HSC COURSE