HES1610 Lecture 1-Unifying Themes in Biology

SARAWAK CAMPUS

SARAWAK CAMPUS

HES1610 Concepts of Biology

The unifying themes of biology:What defines living organisms?

Swinburne University of Technology

BIOLOGY

What is biology?

• Biology is the study of living things

Biology is a huge subject, encompassing many different fields

of science, examples of these are:

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• Microbiology / Immunology

• Molecular biology

• Ecology

• Genetics

• Evolution

• Physiology

• Pathology

• Zoology

• Botany

• Biochemistry


CHARACTERISTICS THAT DEFINE

“LIFE”

Certain characteristics are common to all living organisms

(there are always exceptions in biology)

All of these are exhibited by all living organisms:

1. Growth and development

2. Organization

3. Homeostasis: regulation of metabolism and energy

production

4. Adaptation and evolution

5. Response to stimulus

6. Reproduction

7. Movement

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1. GROWTH AND DEVELOPMENT

All organisms exhibit “growth” during their

lifetime, they increase in:

Size

Structure

Functional complexity

This can involve:

Increase in cell size

Increase in cell number

Both

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1. GROWTH AND DEVELOPMENT

Some organisms:

Grow only over a specific period, after which only

“repair” occurs, not active growth. e.g. most

animals.

Others grow throughout their life. e.g. trees.

Most organisms also exhibit “development”

simultaneous with growth: a change in form

and function, e.g., from fertilized egg to

embryo to young to adult forms.

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2. ORGANISATION

Living things are organised in such a way that all

interactions and activities function

However, if the complex organisation of these

system changes the interactions no longer occur

e.g. The human brain: If a car accident shakes the human brain

up and disrupts the organisation it no longer functions normally

despite the fact that all of the original parts are present

e.g. If you take all of the components from a chloroplast and mix

them together in a test tube, photosynthesis will not occur

In both cases, there needs to be specific

organisation of the components in order for the

appropriate interactions to take place

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2. ORGANISATION

The organisation of these components is a

SYSTEM

In most cases these interaction initially take

place at a cellular level

Cells are organised into structures and structure

correlates to function

• Often analysing a biological structure can give insight into

how it works and what it does

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2. ORGANISATION

The “cell theory”: Based on the work of Schwann and

Schleiden (1838-39):

• All organisms are composed of cells

• All cells come from pre-existing cells

• Cell is the smallest organizational unit of life

Some organisms are composed of single cells

Others are composed of many of cells

Cells divide and produce other cells:

• No cells are created spontaneously from non-living matter.

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2.1 BASIC PROPERTIES OF CELLS

All cells are enclosed by an outer membrane:

Plasma membrane; this separates the inner fluid

(cytoplasm) from the cell’s environment.

All cells have the genetic material: DNA

All cells are capable of self-reproduction

All cells have specific internal structures that

carry out specific reactions and functions

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2.1 BASIC PROPERTIES OF CELLS

There are two basic types of cells:

PROKARYOTIC: those without

membrane bound nucleus and

organelles

e.g. Bacteria (simple cells)

EUKARYOTIC: those with membrane

bound organelles

e.g. Plants, animals, protists, fungi (complex cells)

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2.2 A PROKARYOTIC CELL:

A BACTERIUM

Prokaryotes contain the essentials of cells: DNA, ribosomes, plasma

membrane

It may have: cilia, flagella, cell wall, capsule

They do not contain: a nucleus, chloroplast, mitochondria,

endoplasmic reticulum, Golgi apparatus

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2.3 A EUKARYOTIC CELL:

A PLANT CELL

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2.4 A EUKARYOTIC CELL:

AN ANIMAL CELL

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2.5 SINGLE CELL ORGANISMS

The first living organisms we know of on Earth were single

celled organisms:

They formed Stromatolites, where certain prokaryotes bind thin films of

sediment together

There are still some Stromatolites living of the coast of W.A (Shark Bay)

and in Deer Cave, Gunung Mulu N.P

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2.5 SINGLE CELL ORGANISMS

Many organisms exist as a single cell:

Bacteria

Algae

Some fungi

Plankton

Amoeba

They are simple organisms, but can exists within complex

structures and have complex functions

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2.6 FURTHER ORGANIZATION IN

MULTICELLULAR ORGANISMS

Organisms can also exists as complexes of many cells,

i.e. multicellular organisms

For example:

• Us

• Plants

• Monkeys

• Fish

• Etc..etc..

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2.6. FURTHER ORGANIZATION IN


Cells with similar functions and structures are organized

into a TISSUE

• e.g. Muscle, epidermis.

Various tissues, each with different structure/ functions:

organized together form an ORGAN which has a specific

function

• e.g. Epithelial tissue, muscle tissues together form the

heart,

• e.g. Epidermal cells, mesophyll cells and vascular

tissue form the leaf

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2.6 FURTHER ORGANIZATION IN


In many animals, many organs + tissues together form a

coordinated SYSTEM, with a major function

• e.g. Cardiovascular, digestive systems

Many systems interact to form an ORGANISM: e.g.

• Humans: cardiovascular, respiratory, nervous,

digestive reproductive, immune systems

• Plants: circulatory, reproductive

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2.7 ANIMAL TISSUES AND

SYSTEMS

Epithelial tissue: makes up

human skin and lining of other

body organs

Circulatory system: circulates

blood around the body

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2.8 PLANT TISSUES AND SYSTEMS

Chloroplast Leaf cells

Mesophyll tissue

Leaf: organ

Tree: an

organism

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2.9 FURTHER HEIRCHY IN THE

BIOLOGICAL WORLD

All organisms that can reproduce between themselves, but are

reproductively isolated from others, form a SPECIES

All organisms of a certain species, living within a certain

geographic area, form a POPULATION

The various populations within a certain geographic area

together form a COMMUNITY

The communities, (living organism) and their non-living

environment (water, temperature, light, food, minerals),

together form an ECOSYSTEM

The components of an ecosystem are interdependent for energy

exchanges: form food chains / food webs

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Species in your household:

• Yourself and your family members, dogs, lawn grass, ferns, the

caterpillar on the plants, the snails in the garden, trees

Populations on your street:

• Humans (200); dogs (5); grass plants (5 million) etc.

Your street community:

• The human population + the cat population + the dogs + the grass

plants + the ferns of the one type + the caterpillars + the snails

Your street ecosystem:

• The community + the cars + soil + air + fallen leaves + dog poo +

caterpillars + snails

2.9 FURTHER HEIRCHY IN THE

BIOLOGICAL WORLD

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2.10 A GRASSLANDS/SAVANNA

ECOSYSTEM

Grasslands with scattered trees, herbivores and carnivores +

abiotic (environmental) factors: fire, wind, rain

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2.11 A RAINFOREST ECOSYSTEM

Tall trees + climbing vines + shorter plants + animals living on the

fruits and leaves of these + the abiotic (environmental) factors:

rainfall, sunlight, organic matter

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2.12 AQUATIC ECOSYSTEM

Marine, freshwater (river, lakes), aquarium, mangrove, etc…

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3. HOMEOSTASIS

All organisms carry out a number of chemical reactions, to

obtain the energy required for nutrition, growth and

development, and repair.

Reactions that break up larger molecules into smaller ones and

release their stored energy: CATABOLISM

• e.g. Glucose CO2 + H2O ( + energy)

Reactions that synthesize large molecules from smaller ones

and store energy into these: ANABOLISM

• e.g. Glucose molecules (+ energy) starch or glycogen

Sum of anabolic and catabolic reactions: METABOLISM.

WE WILL STUDY SOME KEY METABOLIC REACTIONS LATER

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3.1 HOMEOSTASIS:

REGULATION OF METABOLISM

All metabolic reactions must be regulated tightly, to

maintain a constant internal environment in cells

WHY IS HOMEOSTASIS ESSENTIAL?

So the cells can obtain the required nutrients, carry out

various biochemical reactions at appropriate rates, not get

overheated and not build up any waste products

HOW IS SUCH REGULATION ACHIEVED?

Through the action of ENZYMES:

Through self-regulation of some reactions by FEEDBACK

MECHANISMS:

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3.2 ENZYMES

Specialized proteins

Biological catalysts: regulate the rates of

biochemical reactions

Carry out specific reactions, efficiently, in specific

cells, under certain conditions, generally in a step-

wise manner, each step being regulated

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We will visit these later.


3.3 FEEDBACK REGULATION

The product of the reaction itself regulates the rate of its

own synthesis, by various mechanisms.

Negative feedback: Most common

The product inhibits (some part of) the reaction

(or the reaction chain)

i.e. When this product exceeds a certain

threshold the reaction shuts down

e.g. When you are hot, your hypothalamus tells

your glands to produce sweat to cool down, once

your body reaches the correct temperature you

stop sweating

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Positive feedback: Less common

The product activates (some part of) the reaction

(or the reaction chain)

i.e. This leads to more production of itself

e.g. When you have a cut and start bleeding,

your platelet will accumulate at the site of the tear

and a clot will form, thus stopping the bleeding

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MECHANISMS

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3.3 EXAMPLES OF HOMEOSTASIS

Regulation of blood glucose: Glucose obtained through food,

then delivered by blood to all cells.

• Too much glucose circulating, it gets stored in liver

• Too little glucose circulating the stored materials converted/broken

down to glucose, or sugar replenished by eating

Regulation of body temperature. Control centre:

hypothalamus in the brain.

• Increase in body temp: blood vessels dilated, sweating increased:

sweat evaporates, skin cooled.

• Drop in temp: sweat glands shut, blood vessels narrowed. Blood

sent to deeper parts of body: reduced heat loss.

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3.3 HOMEOSTASIS

The amount of blood

circulated to the ears is

adjusted according to the

external temp and thus

the heat loss from the

animal.

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4. ADAPTATION AND EVOLUTION

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Adaptation: Inherited traits that help survival and

reproduction of an organism in a particular

environment

Evolution: Change in the genetic composition

of a population over generations

Passing on the traits and mutations that were utilized

for adaptation, as well as mutations that occurred

randomly and survived

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In nature, every advantage increases an animal's chances

of survival, and therefore its chances of reproducing

This simple fact has caused animal species to evolve a

number of special adaptations that help them survive in

their particular environments

Many adaptations revolve around food, as this is essential

for survival:

• Finding food

• Eating food

• Preventing them from becoming food - camouflage

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Adaptations can be:

Physical, physiological, behavioural,

For feeding, or withstanding adverse conditions, or

self-protection etc

e.g. Fur of polar bears, streamlined bodies of fish/birds,

light bones of birds, legs of kangaroos, camouflage of

some animals, changes in human anatomy

The ability of a population to adapt and

evolve is essential for its survival over

generations

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Wings create airfoils:

• Changes in air current that produce lift


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The upright human

body: supported by

backbone + rib

cage+ skull

The joints allow

flexibility and precise

manipulations

ADAPTATION AND

EVOLUTION

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Why humans walk on 2 legs?

ADAPTATION AND EVOLUTION

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http://ngm.nationalgeographic.com/2006/07/bipedal-body/video-interactive


Over 6 million years: brain size increased, jaws shortened and flattened,

skeletal modifications, changes in food, upright walking, development of

language, learning, social systems

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EVOLUTION OF THE GALAPAGOS FINCHES

ACCORDING TO FOOD SOURCE

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CAMOUFLAGE

A gecko/lizard resembles dry

leaves

Batesian mimicry: When in danger, the larva of hawkmoth (an insect) resembles a snake!46

A praying mantis

A green vine

snake


CAN YOU RECOGNIZE THIS??

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5. RESPONSE TO STIMULUS AND

ENVIRONMENT

All organisms respond to stimuli

Stimulus: physical or chemical change, in the internal or external

environment of an individual. e.g. Changes in intensity or direction of light

Sound

Smell

Pressure

Gravity

Touch

Changes in amount/ composition of soil, water, air

The nature of response may vary

• e.g. Simple cells may move towards / away from light, plant shoots

grow towards light, roots grow towards gravity, some plants (touch-me-

not, Venus flytrap) respond to touch, animals respond to sounds, smell.

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5.1 PHOTOTROPISM:

RESPONSE TO LIGHT

Shoots grow towards light, roots grow away from it

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5.2 GRAVITROPISM:

RESPONSE TO GRAVITY

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Roots grow towards gravity,

shoots grow away from it


5.3 THIGMOTROPISM:

RESPONSE TO TOUCH

Touch-me-not:

Touching causes rapid

loss or water from the

base of leaves: they

close (loss of K+,

followed by loss of

water).

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5.4 PHOTOPERIODISM

Response to season

A physiological response to the relative

lengths of night and day

Some plants flower during summer, others

during spring or autumn, some trees shed

there leaves in autumn so they have no

leaves in winter

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5.5 ANIMALS RESPOND TO

STIMULI TOO

What do bears do in winter? Why?

What happens to our pupils (eye) when the

light is bright?

What do dogs do when they get hot?

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6. REPRODUCTION AND HEREDITY

The ability of a species to reproduce, i.e., to produce offspring

like itself, is key to its survival

Genetic information in cells is contained in the form of DNA,

which has the ability to make identical copies of itself

DNA is thus passed on from parent cells to daughter cells, and

from parents to offspring

DNA stores the genetic information in the form of instructions on

how to make proteins, proteins carry out various biochemical

reactions in the body and are also structural components of cells.

MORE LATER: IN GENETICS

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DOES THIS MEAN THE GENETIC

MATERIAL IS STATIC?

Genetic variability between individuals is created

by different mechanisms:

Collectively called MUTATIONS

Mutations lead to a change in the sequence of

DNA, this causes changes in the instructions for

making proteins and thus cell’s functions

The changes are inherited by the next

generations of cells and thus organisms

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7. MOVEMENT

All living organisms move, or are

capable of movement.

Movement by:

Flagella, cilia, pseudopodia, legs, wings,

fins, etc.

Movement may or may not be obvious.

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7. MOVEMENT

Sometimes movement is restricted to early

developmental stages

• e.g. Larvae, adults are fixed to a support (e.g. corals,

sponges), but still may have cilia/ flagella that beat in the

water and gather food

Plants do not appear to move, however,

• Their leaves move towards light

• Some plants also turn their flowers towards the sun;

• Others show obvious movement in response to certain

stimuli (e.g. certain insectivorous plants).

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MOVEMENT: VENUS FLY-TRAP

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IN SUMMARY

The living world, no matter how diverse, still

has some unifying characteristics which are

shared by all:

GOHARRM

Growth, organisation, homeostasis, adaptation,

response to stimulus, reproduction, movement

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IN SUMMARY

Now apply this information to the following

situations to work out if these are living

organisms or not

Are viruses living or nonliving?

Are seeds living or non-living?

Are salt or sugar crystals growing in a saturated solution

living or nonliving?

Are we living?

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HES1610 Lecture 1-Unifying Themes in Biology

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