Post on 12-Jan-2016
What is Biology?
Science: A way of using organized evidence to learn about the natural world.
Biology: The branch of science that deals with living things.
So….what are living things?
Living things… Are made up of cells. Reproduce.
Sexually (humans) Asexually (bacteria)
Are based on a genetic code. Grow.
So….what are living things?
Living things… Obtain and use nutrients and energy.
Photosynthesis & Cellular Respiration Respond to their environment. Maintain a stable internal environment.
Homeostasis Change over time.
Evolution!!!
What is the Scientific Method?
1) Question 2) Hypothesis
It must be TESTABLE!!!
What is the Scientific Method?
3) Experiment Procedure (step-by-step) Controls
What stays the same. Independent Variables
What you change….ONE THING ONLY!!! Dependent Variables
What happens based on your experimental design….the results.
What is the Scientific Method?
4) Observations Qualitative….a description.
“The bread is cold.” Quantitative….a measurement.
“The bread is 12.4 degrees Celsius.”
5) Results 6) Conclusion (based on facts) vs.
Inference (based on opinions and unobserved information)
What are the major “levels of organization” of living things?
1) Atoms…not living. Hydrogen, Helium, Oxygen
2) Molecules…not living. Water, Ammonia, Carbon Dioxide
3) Cells…smallest unit of life. Brain cell, bacteria
What are the major “levels of organization” of living things?
4) Groups of cells Tissue, organ, organ system.
5) Organism Human, Bison, Sunflower
6) Population …group of ONE organism Herd of buffalo, field of sunflowers
What are the major “levels of organization” of living things?
7) Community…populations of different organisms living together Herd of bison AND a field of sunflowers.
8) Ecosystem…community (living things) AND non-living surroundings Bison herd, sunflower field, soil, air, water.
9) Biosphere…the Earth!
Section 3.1
Review “Levels of Organization” Individual Organism Population Community Ecosystem Biome Biosphere
How does energy flow?
All energy originates from SUNLIGHT or CHEMICAL COMPOUNDS.
Autotrophs: use energy from sunlight or chemicals to produce food. Also called PRODUCERS
How does energy flow?
Photosynthesis: the chemical process that uses energy from sunlight to convert H2O and CO2 to sugar and O2 Plants, algae
Chemosynthesis: the process that uses energy from chemicals to create carbohydrates….without light! Bacteria that live in ocean floor vents
How does energy flow?
Heterotrophs: organisms that rely on other organisms for their energy Also called CONSUMERS
Herbivores– plant-eaters Carnivores– meat-eaters Omnivores– eat plants AND meat Detrivores– feed on dead plant/animal
matter Decomposers– break down organic matter
How does energy flow?
Food chain: displays the one-way energy flow from sun (or chemicals) to autotrophs to heterotrophs
Sun producer 1st-level consumer 2nd-level consumer 3rd-level consumer
How does energy flow?
Food web: More realistic way of representing energy flow in nature…shows complex feeding relationships
What are trophic levels?
1st trophic level: PRODUCERS 2nd trophic level: Primary (1st-level)
consumers 3rd trophic level: Secondary (2nd-level)
consumers And so on….
What are energy pyramids?
Only PART of the total energy from one trophic level is passed on to the next trophic level within a food web.
(approximately 10% is passed on within each transfer)
Corn—75 ‘units’ of energy Cow—7.5 ‘units’ of energy Human—0.75 ‘units’ of energy
Where does all of the “lost” energy go?
The “lost” energy (90% of the total at each trophic level) is used in two ways:
1) Used as energy for life processes Growing, Reproducing, Moving, etc.
2) Lost as heat
What is a biomass pyramid?
Biomass: the total amount of living tissue within a given trophic level
This pyramid also usually is reduced by a factor of ~ten at each trophic level.
500,000 g of corn (plant tissue) 50,000 g of cows (1st-level consumer
tissue) 5,000 g of human tissue
How are energy pyramids related to biomass pyramids?
***Because each trophic level harvests only about 1/10th of the energy from the level below, it can support only about 1/10th the amount of living tissue.***
How is the movement of matter different from the movement of energy within an ecosystem?
Energy flows in ONE DIRECTION!!
Matter is RECYCLED!!
How is water cycled?
Evaporation: Liquid to gas
Condensation: Gas to liquid
Precipitation: Liquid in atmosphere to liquid on ground
How is water cycled?
Runoff: Liquid remains on surface
Seepage: Water soaks into ground
Transpiration: Liquid IN PLANTS to gas IN ATMOSPHERE (evaporation through leaves)
How is carbon cycled?
Refer to p. 54-55 in your textbook.
Photosynthesis: takes carbon out of atmosphere
Respiration: releases carbon into atmosphere
Human activities: release (excess) carbon into atmosphere
What shapes an ecosystem?
Biotic factors: biological influences on an organism Predators, prey, population overcrowding
Abiotic factors: physical (non-living) influences on an organism Temperature, soil, precipitation, sunlight
What shapes an ecosystem?
Together, BIOTIC and ABIOTIC factors determine the survival and growth of organisms within an ecosystem.
What is a habitat? A niche?
Habitat: The area where an organism lives.
Niche: The role of an organism within a given ecosystem.
What is a niche?
The niche of a bullfrog:Eats insects, minnowsIs eaten by snakes, raccoons,
birdsLives In or near lakes or streamsAdapts by burrowing in pond mud
to hibernateReproduces by laying eggs in
water during warm months
What is a niche?
NO TWO SPECIES CAN OCCUPY THE SAME NICHE AT THE SAME TIME IN THE SAME ECOSYSTEM!!!
This is the Competitive Exclusion Principle!
What are the 3 major interactions within an ecosystem?
1) CompetitionTwo organisms fighting for
use of a single resource at the same place at the same time…one of them will lose and not survive.
What are the 3 major interactions within an ecosystem?
2) Predation One organism kills and feeds on
another organism.
What are the 3 major interactions within an ecosystem?
3) Symbiosis Mutualism
Both species benefit (Bird & Rhino) Commensalism
One benefits, one doesn’t care (Remora & Shark)
ParasitismOne benefits, one is harmed
(Fleas/Ticks/Worms & Dog)
What is succession?
Succession: the predictable series of changes experienced by an ecosystem over time.
What is primary succession?
Primary succession: Succession that begins with BARE ROCK.
Pioneer species (usually lichens) small grasses shrubs trees
What is secondary succession?
Secondary succession: Succession that begins with SOIL…usually after a disturbance (farming, forest fire, etc.)
What are major characteristics of populations?
1) Geographic distribution Where does the population live?
2) Population density How crowded is the population?
3) Growth rate How fast does the population grow?
4) Age structure How old (or young) is the entire population?
What factors affect growth rate? Three factors affect growth rate:
1) Birth rate 2) Death rate 3) Emigration/Immigration
Emigration: individuals leaving the populated area
Immigration: individuals entering the area
HOW do populations grow?
There are 2 general patterns in which populations of organisms can grow.
1) Exponential Growth 2) Logistic Growth
What is exponential growth?
Exponential growth: (J-curve) Individuals within a population grow at a constant rate over time.
NEED: Limitless food Limitless water Limitless space No predators No disease
What is logistic growth?
Logistic growth: (S-curve) Occurs when a population’s growth slows or stops after a period of exponential growth.
Growth slows or
stops when food,
shelter, etc. become
less available!
What is logistic growth?
For a given population, growth slows or stops near a certain number. This number varies within every environment, based on the amount of resources available within that environment.
This number of individuals that a given environment can support is called the CARRYING CAPACITY!!
What is logistic growth?
What affects carrying capacity? BIOTIC and ABIOTIC factors!!! Temperature Precipitation Shelter Food Disease
What limits populations during logistic growth?
Limiting factors: cause the growth of a population to slow or stop 1) Competition 2) Predation 3) Parasitism and disease 4) Drought and other climate factors 5) Human disturbance
What are density-dependent limiting factors?
Density-dependent factor: a limiting factor that depends on POPULATION DENSITY!
Competition…for food, water, space, sunlight
Predation…deer / moose-wolf example Disease Anything else related to overcrowding!!
What are density-independent limiting factors?
Density-independent factor: a limiting factor that affects all populations in the same ways, regardless of the density of the population.
Weather (floods, storms, etc.) Natural disasters Human activities (roads, logging, dams,
etc.)
What are age structure diagrams?
Age structure diagrams: display the numbers of people within different age groups in a population. Good predictor of future population growth!
P. 62-63 #1-8, 13-15, 17-22
Read p. 132-134
p. 136-137 #5, 10-12
What is demography?
Demography: the study of human populations
What is happening to the human population?
From 10,000 B.C. until 1500 A.D., growth was very slow.
From 1500-2006 (and especially 1800-2006), growth has been exponential!! WHY?
Agriculture Industry/Technology Health care
What is happening to the human population?
As societies become more modern, increase their level of education, and raise their standard of living, birth rates fall AND death rates fall.
When the birth rate is LOWER than the death rate, population growth stops, and that population has undergone the demographic transition.
What is happening to the human population?
Areas such as JAPAN, UNITED STATES, and EUROPE have completed the demographic transition.
Many areas within AFRICA, ASIA, and SOUTH AMERICA have NOT…their populations are still growing rapidly!!
How do humans affect the biosphere?
Humans affect the biosphere by…
Hunting and gathering Agriculture Industry Urban Development
What developments have led to human population growth?
Agriculture: provided sustainable food resources for large amounts of people
Green Revolution: Use of chemical fertilizers, pesticides, and modern techniques to greatly increase the world’s food supply.
Industry/Urban Development: More technology = easier life = longer life span and more babies!!
What are natural resources?
Renewable resources: regenerate (alive) OR replenished by matter cycles Wood Water Nitrogen
Nonrenewable resources: cannot be replenished naturally Oil Gas Coal
What are natural resources?
Nonrenewable resources are running out as more and more people use them!!
Renewable resources can also be severely damaged in both quality and quantity as more and more people use them…water pollution, deforestation, etc.
What are natural resources?
How do we use resources responsibly?
Sustainable development: Using natural resources responsibly without depleting them or reducing their quality
What are natural resources?
Types of resources include… Land resources– coal, oil, soil Forest resources– trees, animals Fishery resources– fish Air resources– O2 (+ ozone/greenhouse layer) Freshwater resources– drinking water, animals
ALL of these can be negatively affected by human development and activity!!!
What is biodiversity?
Biodiversity: biological diversity (diversity…differences)
Species diversity Ecosystem diversity Genetic diversity
The MORE biodiversity, the BETTER!!
What threatens biodiversity?
The following factors threaten biodiversity:
Habitat reduction or fragmentation Overhunting/fishing Pollution Invasive species…(kudzu, zebra mussels, etc.) Ozone depletion = more UV rays hitting Earth (from
CFCs) Global warming
What is the greenhouse effect?
Greenhouse effect: the situation in which solar heat is retained by a layer of “greenhouse gases” to warm the Earth and maintain a constant temperature.
Greenhouse gases include: Carbon dioxide Methane Water vapor
Is the greenhouse effect bad?
NO!!! Under normal circumstances, the greenhouse effect is not bad.
BUT, because air pollution is making the “blanket” of greenhouse gases thicker, MORE heat is being trapped inside the Earth, leading to GLOBAL WARMING.
What else affects climate?
1) Latitude The angle of sunlight is more DIRECT at
the equator, and therefore this zone is warmer.
Tropical Zone: Direct sunlight...hot Temperate Zone: Moderate sunlight…
seasonal temperature changes Polar Zone: Very angled, indirect sunlight…
cold
What else affects climate?
2) Winds 3) Ocean currents
Both rely on the following principle: Hot air/water RISES Cold air/water SINKS
What are the 4 states of matter?
Solid: arranged in a DEFINITE PATTERN, with a definite shape and a definite volume that never changes.
Liquid: have a definite volume that never changes, but does NOT have a definite shape
What are the 4 states of matter?
Gas: particles move very fast and can be very spread out…have no definite shape AND no definite volume (they can expand and shrink)
Plasma: gases heated to above 5000o C.
Electrons are knocked away from the atoms because they collide very violently.
What is the basis of chemistry? The atom: “unable to be cut”; the basic
unit of matter Proton (+)
Within nucleus Neutron (O)
Within nucleus Approximately the same mass of a proton.
Electron (-) Orbits around nucleus 1/1840 the mass of a proton!!!
What is the Periodic Table?
Atomic Number # of protons in an atom
Mass Number # of protons + # of neutrons in an atom
The Periodic Table is organized numerically by atomic number.
What are atoms? Atoms (elements) are usually NEUTRAL…they
have the same number of protons as electrons. One atom makes up a specific ELEMENT, which cannot be broken down into smaller parts.
Isotopes have different numbers of neutrons than regular elements. Therefore, they have a different mass number!!!
Ions have different numbers of electrons than regular elements.
What is a compound?
A chemical compound is a substance formed by the chemical combination of two or more elements. NaCl H2O
The MOLECULE is the smallest unit of compounds.
What are the two types of chemical bonds?
Ionic Bonds Electrons are TRANSFERRED between
atoms. “+ vs. –” attraction
Covalent Bonds Electrons are SHARED between atoms.
What happens when compound combine?
Mixture: Salt and Pepper Can be PHYSICALLY separated!!!
Solution: Saltwater (dissolved particles) Solute—salt Solvent—water
Suspension: Blood (undissolved particles)
What are acids, bases, and pHs?
In a solution, H20 dissolves to form H+ and OH- ions.
pH measures the ratio of H+ to OH- ions in a solution.
What are acids, bases, and pHs?
Acid pH 0.1 to 6.9 More H+ ions than OH- ions
Base pH 7.1 to 14 More OH- ions than H+ ions
What are acids, bases, and pHs?
Neutral Substance pH 7 H+ and OH- concentration is equal
Buffer Maintains homeostasis by controlling
sudden pH changes.
What is carbon?
All living things on Earth are primarily composed of CARBON (and water).
WHY? It is very easy for the carbon atom to form
bonds with other carbon atoms and with many other different elements.
Therefore, carbon is an ‘ingredient’ in MANY natural molecules….also called ORGANIC MOLECULES.
What is a macromolecule?
Macromolecule: “giant molecule” Most macromolecules are based upon
carbon and are called polymers.
Monomers (small units) join together to make polymers (large units—chains).
What are the 4 major natural polymers?
Carbohydrates Lipids Nucleic Acids Proteins
What are carbohydrates?
Carbohydrates: composed of C, H, O.
Used as an energy source for living things.
3 categories: Monosaccharides—glucose, fructose Disaccharides-- sucrose Polysaccharides– glycogen, starch,
cellulose
What are lipids?
Lipids: composed of mostly C, H. Not soluble in water. Used as energy storage for living things. Part of the cell membrane for animal cells. Made up of FATTY ACIDS and GLYCEROL
Three categories: Fats Oils Waxes
What are nucleic acids?
Nucleic acids: composed of H, N, O, C, P.
Molecules are called nucleotides. Used as storage and transfer device for
genetic information.
Two categories: DNA (deoxyribonucleic acid) RNA (ribonucleic acid)
What are proteins?
Proteins: composed of N, C, H, O. Made up of chains of AMINO ACIDS.
These chains are joined by PEPTIDE BONDS.
Used for: regulation of cell processes formation of bones/muscles transportation of substances fighting disease cell structure components enzymes
How do chemical reactions work?
Chemical reaction: process that changes one set of chemicals to another set of chemicals by breaking bonds and forming new ones.
You START with reactants. You FINISH with products.
What are some examples of chemical reactions?
2H2 + O2 2H2O
6H2O + 6CO2 C6H12O6 + 6O2
CH3CO2H + NaHCO3 CO2 + NaCO3 + H2O
What is activation energy?
Activation energy: the energy needed to start a chemical reaction
Catalysts: speed up chemical reactions by reducing the amount of activation energy needed to start them
What are enzymes?
Enzymes: proteins that are natural catalysts!!!
Enzymes provide a site for a chemical reaction to take place.
How does an enzyme-influenced chemical reaction occur?
1-- Reactants (called SUBSTRATES) bind to the ACTIVE SITE of an enzyme.
2-- (Sped-up) chemical reaction takes place.
3-- Products are released from the enzyme.
How does an enzyme-influenced chemical reaction occur?
Substrate = Key
Enzyme = Lock
Active Site = Keyhole within the lock
(7.1) How were cells discovered?
Robert Hooke (1665): First microscope…looked at cork and discovered tiny, empty chambers—PLANT CELLS!!
Anton van Leeuwenhoek (1665-ish): First used microscope to observe LIVING cells in pond water.
What is the cell theory?
By 1839, scientists concluded that all plants and animals were made of cells.
This discovery (and related discoveries) led to the formation of the cell theory: 1) All living things are made of cells. 2) Cells are the basic units of structure and
function in living things. 3) New cells are produced from existing
cells.
How are cells investigated today?
Fluorescent labels of cell components. 3-D imaging. Electron microscopes (3-D and 1000X
more magnified than light microscopes).
What is the difference between prokaryotes and eukaryotes?
Eukaryotes: cells that contain a nucleus Larger and more complex Genetic material (DNA) is inside nucleus Contain organelles
Plants, animals, fungi, protists
What is the difference between prokaryotes and eukaryotes?
Prokaryotes: cells that do not contain a nucleus Smaller and simpler Have genetic material (DNA), but not
inside a nucleus Usually no organelles, except ribosomes
Bacteria
(7.2) What are organelles?
Organelles: “tiny organs”…small structures within cells (eukaryotes) that perform specific functions
Reside in the cytoplasm Cytoplasm: portion inside the cell that is
OUTSIDE the nucleus
Organelle Overview
1) Nucleus: Contains DNA to provide instructions for cell functions.
2) Ribosomes: Small spheres on which proteins are assembled.
3) Endoplasmic Reticulum: Ribosomes reside on the rough ER; lipids are made on smooth ER
Organelle Overview
4) Golgi apparatus: Modifies, sorts, and packages proteins and other cell products for storage or export.
5) Lysosomes: Filled with enzymes to break down food (or waste) products.
6) Vacuoles: Storage tanks for food/water.
Organelle Overview
7a) Mitochondria (animal/plant cells): convert food into energy. Contain their own DNA.
7b) Chloroplasts (plant cells): convert sunlight into food Contain their own DNA.
Organelle Overview
8) Cytoskeleton: help provide shape and structure to the cell. Microfilaments: provide tough, flexible
support Microtubules: assist in cell division AND
cell transportation through CILIA and FLAGELLA
What is the endosymbiotic theory?
Endosymbiotic theory: Since mitochondria and chloroplasts have their own DNA, they were likely prokaryotes (separate cells) that formed a symbiotic relationship with larger eukaryotes and resided inside eukaryotic cells. Later, these prokaryotic cells just evolved into organelles (mitochondria and chloroplasts).
(7.3) What is the function of the cell membrane?
Cell membrane: regulates what enters and leaves the cell (and how much of it) Provides protection Provides support Lipid Bilayer
Contains protein channels to allow for passing of materials
What is a cell wall?
Cell wall: provides support and protection for the cell Only in plants, fungi, and some
prokaryotes Very rigid Carbohydrate and protein composition Very porous, so cannot regulate anything
that passes through.
(7.4) How do cells make organisms?
Unicellular organisms: a single cell that IS an organism!
Multicellular organisms: organisms made up of many SPECIALIZED cells Blood cells (oxygen transport) Pancreatic cells (enzymes for food
digestion) Muscle cells (movement)
How do cells make organisms?
Plants have many different types of specialized cells too… Guard cells (regulate gas exchange) Vascular cells (water/nutrient transport)
What are the major levels of organization in living things?
1) Cell 2) Tissue 3) Organ 4) Organ System
What are the major levels of organization in living things?
Tissue: groups of similar cells
Organ: groups of similar tissues
Organ system: groups of similar organs
***Specialized cells WORK TOGETHER to allow organ systems to work and INTERACT to allow all bodily processes to function!!!
(7.3) What is the function of the cell membrane?
Cell membrane: regulates what enters and leaves the cell (and how much of it) Provides protection Provides support Lipid Bilayer
Contains protein channels to allow for passing of materials
What is a cell wall?
Cell wall: provides support and protection for the cell Only in plants, fungi, and some
prokaryotes Very rigid Carbohydrate and protein composition Very porous, so cannot regulate anything
that passes through.
What is diffusion?
Every living cell NEEDS to exist in a very exact liquid environment, or it will DIE.
Concentration: mass of particles in a volume of liquid
12 g salt in 6 L water 2 g/L
What is diffusion?
Diffusion: movement of particles from an area of higher concentration to an area of lower concentration Diffusion stops only when a cell system
has reached equilibrium.
What is diffusion?
Diffusion does NOT require any energy from the cell, therefore is called “passive transport”.
What is osmosis?
Osmosis: the diffusion of WATER through a selectively permeable membrane.
Water wants to DISSOLVE an area of high particle concentration.
What is osmosis?
Isotonic: Both portions of the solution are of the same concentration.
If two portions of a solution have UNEQUAL concentrations, then… Hypertonic: The portion of the solution
with the higher concentration Hypotonic: The portion of the solution with
the lower concentration.
What is osmosis?
If a cell is in a hypertonic solution, then water moves OUT of the cell in order to dissolve the outside solution, and the cell SHRINKS.
If a cell is in a hypotonic solution, then water moves IN to the cell in order to dissolve the solution within the cell, and the cell EXPANDS.
What is facilitated diffusion?
Facilitated diffusion: Movement of particles from higher concentration to lower concentration….BUT:
For particles that are too large to pass through the lipid bilayer….particles instead pass through protein channels
Since this is still a type of diffusion, it requires NO energy (passive transport).
What is active transport?
Active transport: movement of particles from an area of lower concentration to an area of higher concentration Uses protein channels…”pumps” Requires ENERGY!!
What is endocytosis? Endocytosis: the process of taking
materials (usually food) into a cell through pockets within the cell membrane. Phagocytosis: “cell eating”…large food
molecules Pinocytosis: “cell drinking”…liquids
Exocytosis: the release of material (usually waste) from a cell
What is exocytosis?
Exocytosis: the release of material (usually waste) from a cell
(8.1) What is photosynthesis?
Autotrophs: organisms that make their own food
Heterotrophs: can’t make their own food, so they EAT it
ATP: (adenosine triphosphate) chemical compound used to release ENERGY
What is photosynthesis? ATP: (adenosine triphosphate) chemical
compound used to release ENERGY ADP: (adenosine diphosphate)
“uncharged battery” compound within organisms used to store energy When an organism wants to STORE
energy, it adds a third phosphate molecule to ADP to produce ATP, which acts as a “charged battery”
When an organism wants to RELEASE energy, it breaks the chemical bond between the 2nd and 3rd phosphate molecule.
What is photosynthesis?
Energy from ATP can be used for… Active transport (across cell membranes) Muscle contraction (movement) Protein synthesis (within ribosomes) Light production (in fireflies)
What is photosynthesis?
Problems with ATP… ATP cannot store energy for a long time (it
loses its “charge” easily
SO, energy is stored within ADP and other large ‘storage’ molecules such as GLUCOSE, and the energy from glucose is used to add a ‘P’ to ADP to produce ATP only when needed.
(8.2) How was photosynthesis discovered?
Photosynthesis: plants use energy from sunlight to convert water (H2O) and carbon dioxide (CO2) into carbohydrates (glucose…C6H12O6) and a waste product—oxygen (O2).
H2O + CO2 + sunlight C6H12O6 + O2
How was photosynthesis discovered?
Where does a tree’s increase in mass come from as it grows over the years???
THREE EXPERIMENTS… 1) Van Helmont (1600s): most of a plant’s
mass as it grows comes from WATER
2) Priestley (1700s): plants release OXYGEN when they grow (candle expt.)
How was photosynthesis discovered?
3) Ingenhousz (late 1700s): in order to produce oxygen, a plant needs LIGHT
(He just repeated Priestley’s expt., but ran one test in the dark and one in sunlight)
6CO2 + 6H2O ----light---> C6H12O6 + 6O2
What else do plants need to undergo photosynthesis?
Plants need carbon dioxide and water, but they ALSO need a molecule called CHLOROPHYLL (housed in chloroplasts) to capture energy within sunlight
Sunlight is not “white”…it’s actually a mix of violet, blue, green, yellow, orange, & red
What else do plants need to undergo photosynthesis?
Chlorophyll ABSORBS energy from sunlight. Two types…
Chlorophyll ‘b’ absorbs violet and blue light Chlorophyll ‘a’ absorbs yellow, orange, & red
light
(the only color of sunlight that is NOT absorbed is green….green is therefore REFLECTED, and that is why most plants appear to be green!!!)
What else do plants need to undergo photosynthesis?
The energy that is absorbed from the sunlight is used to drive the chemical reaction that breaks down CO2 and H2O to make the sugars and oxygen within photosynthesis!
(8.3) What makes up a chloroplast?
(Photosynthesis takes place inside chloroplasts) Thylakoids: sac-like membranes arranged
in stacks called GRANA Light-dependent reactions take place here.
Stroma: region outside the thylakoid membranes
Light-independent (dark) reactions take place here.
Also called Calvin Cycle
What is photosynthesis?
Photosynthesis consists of TWO major chemical reactions… Light-dependent reactions
Need sunlight Use H2O to produce ATP, NADPH, and O2
Calvin Cycle Use CO2 and ATP/NADPH to produce sugars (and send ADP/NADP+ back to light-
dependent reactions)
What happens within the Calvin Cycle?
During the Calvin Cycle, ATP and NADPH that are created during the light-dependent reactions are used to fuel the production of glucose.
What happens within the Calvin Cycle?
Overall, 6 CO2 molecules are used to make a single 6-carbon sugar (glucose)!!!
What factors affect photosynthesis?
Factors that affect photosynthesis include…
1) Drought…plants need H2O in light-dependent reactions!!
2) Temperature…photosynthesis works best between 0-35o Celsius.
3) Light Intensity…shade/sun factors into the speed of photosynthesis.
What is cellular respiration?
Cellular respiration: process that releases energy by breaking down glucose (and other food molecules) in the presence of oxygen
6O2 + C6H12O6 6CO2 + 6H2O + energy
What is cellular respiration?
Cellular respiration takes place in the MITOCHONDRIA!!!
3 major stages of cellular respiration…
1) Glycolysis
2) Krebs Cycle (a.k.a. Citric Acid Cycle)
3) Electron Transport Chain (ETC)
ALL THREE STAGES PRODUCE ATP!!!
What is glycolysis?
Glycolysis: first step in releasing the energy of glucose 1 molecule of glucose is broken down into
two molecules of pyruvic acid…simply broken in half
Uses 2 ATP molecules to break down glucose, but 4 ATP’s are produced!
A “net gain” of 2 ATP’s!!
What is glycolysis?
AFTER glycolysis, two processes may occur…
If oxygen IS present, the Krebs Cycle occurs.
If oxygen IS NOT present, fermentation occurs.
What is fermentation?
Fermentation: the release of energy from food molecules by producing ATP in the absence of oxygen (anaerobic environment) Very inefficient when compared to aerobic
processes
1) Alcoholic fermentation (in yeast) 2) Lactic acid fermentation (in humans)
What is fermentation?
Lactic acid fermentation: occurs within muscle cells of animals when insufficient oxygen is available Lactic acid causes “burning muscles” after
running or working out!!!
(9.2) What happens after glycolysis (when there is oxygen)?
Remember…after glycolysis, if there is no oxygen, then fermentation occurs.
If there IS oxygen, then the Krebs Cycle occurs.
At the end of glycolysis, 90% of the energy within glucose is still available…we need to extract it!!!
What happens after glycolysis (when there is oxygen)?
Aerobic: with oxygen Anaerobic: without oxygen If there IS oxygen, then the Krebs Cycle
occurs.
Krebs Cycle (citric acid cycle)…pyruvic acid is broken down into carbon dioxide, and energy is released.
What is the ETC?
ETC: uses “batteries” produced during Krebs Cycle to produce more ATP.
How much ATP is produced during cellular respiration?
For each glucose molecule…
Glycolysis: 2 ATPs are made
Krebs Cycle/ETC: 34 additional ATPs are made
36 TOTAL ATPs (with oxygen) Only 2 total ATPs (without oxygen)
What makes up DNA?
Ingredients of DNA include…
Nucleotides: sugar (deoxyribose), phosphate group, nitrogenous base.
Nucleotides, chained together, form a DNA molecule.
There are 4 n-bases in DNA Adenine, Guanine, Cytosine, Thymine (A, G,
C, T)
What are Chargaff’s rules?
G always matches with C A always matches with T
What is a double helix?
Watson and Crick: discovered structure of DNA molecule
Double helix:
“twisted ladder”
(12.2) How does DNA replicate?
Prokaryotes: usually have ONE circular DNA molecule
Eukaryotes: usually have MULTIPLE elongated DNA molecules
How does DNA replicate?
Chromosomes are SO long, they have to be tightly wrapped in order to fit into a cell’s nucleus!
There is over 1 meter of DNA in each nucleus of each human cell!!!!!!!!!!!!!!
How does DNA replicate?
DNA “coils” in the following way…
1) DNA wraps around histones (protein spheres) to form nucleosomes (bead-like DNA/histone combo)
2) Nucleosomes coil/wrap around each other very tightly to form a chromosome.
How does DNA replicate?
DNA replication… 1) DNA splits at multiple locations along the
strand at replication forks. DNA polymerase enzyme ‘unzips’ double strand. (Hydrogen bonds connecting strands are broken.)
2) Two strands of “double helix” completely separate.
3) New n-bases attach to each original strand (A-T and C-G) to form two new “complementary strands”.
4) Both new double-stranded molecules “twist” into a double helix.
How does DNA replicate?
Before replication: 1 double helix
After replication: 2 double helices Each with one original strand and one
complementary strand! (Semi-conservative replication.)
(12.3) How does RNA differ from DNA?
Genes are coded in DNA…..but, you must DECODE the DNA!!!
RNA is a molecule that assists in the gene decoding process.
(DNA contains the instructions to make proteins, but RNA actually participates in the protein-making process.)
How does RNA differ from DNA?
RNA is different from DNA in these ways:
1) RNA’s sugar is ribose, not deoxyribose 2) RNA is single-stranded, not double-
stranded 3) RNA contains Uracil instead of Thymine
A, C, G, U instead of A, C, G, T
What is RNA?
Three types of RNA… 1) Messenger RNA (mRNA): messengers from
DNA to the rest of the cell (specifically ribosomes)
2) Transfer RNA (tRNA): assists in the assembly of proteins during translation
3) Ribosomal RNA (rRNA): ingredient of ribosomes
What is transcription?
Transcription: the process of copying nucleotide sequences from DNA into a complementary sequence in RNA
Process… 1) RNA polymerase (enzyme) “unzips”
double-stranded DNA in nucleus. Bind at PROMOTERS (“start signal” areas
of DNA)
What is transcription?
2) One strand of DNA (template strand) is used to assemble a complementary strand of RNA. T A, A U, G C, C G
3) RNA is sent from the nucleus to the ribosome for TRANSLATION
How is RNA edited?
Introns: DNA sequences that are “useless” in protein production
Exons: DNA sequences that code for proteins….”useful”
To finish transcription, introns are cut out and the remaining exons are “glued” back together so 100% of the new RNA molecule is “useful”.
How does one read the genetic code?
Codon: three nucleotides that specify a single amino acid Amino acid = ingredients of proteins
RNA = UCGCACGGU Three codons are ‘UCG’ ‘CAC’ ‘GGU’ UCG Serine (amino acid) CAC Histidine GGU Glycine
What is translation?
Translation: process of decoding an mRNA message into an amino acid chain to produce a PROTEIN. (see Fig. 11.9 on p. 294)
Process… 1) mRNA attaches to a ribosome. 2) Each codon on mRNA is “read” and the
proper amino acid is attached to a chain by tRNA.
3) Protein chain is complete when a “STOP” codon is read.
(12.4) What are mutations?
Mutations: changes in genetic material Caused by mistakes in copying DNA
Inserting an incorrect n-base Skipping an n-base
What are mutations?
Gene mutations: occur in a single gene Chromosomal mutations: occur and
produce changes in a whole chromosome
What are mutations?
Point mutations: change one or a few n-bases; occur at a single point in the DNA sequence
What are mutations?
Frameshift mutations: addition or deletion of an n-base that shifts the reading frame of the gene More dangerous than point mutations b/c
they can alter the ENTIRE amino acid sequence instead of just one amino acid…ALL codons can be affected!!!
What are mutations?
Chromosomal mutations: changes in the number or structure of entire chromosomes May delete entire genes, change location
of genes, or make extra copies of genes
Why are mutations important?
Most mutations are NEUTRAL…they have no effect on protein production and gene function.
Harmful mutations cause genetic disease, cancers, etc. (Ch. 14)
Beneficial mutations increase genetic variability in organisms and allow species to evolve more quickly by adapting to the environment.
(12.5) How and when are genes expressed?
Not all genes in a cell are expressed all the time.
GENE REGULATION controls when genes should be turned “on” for transcription/translation and when they should be turned “off”
How are genes regulated?
Genes usually contain specific regions for regulation Promoter (RNA polymerase binds to start
transcription) Operator (Repressor can bind to this
region to turn gene “off”; if repressor is NOT bound to operator, gene is “on)
Coding sequence (the actual n-base code for amino acid/protein production)
Stop sequence
How are genes regulated?
Gene regulation is ALWAYS important, but is extremely important during embryonic growth. Certain genes need to be turned on/off at
specific times in order for an organism to grow and differentiate correctly.
DIFFERENTIATION: process that occurs that causes cells to become specialized in structure and function…stem cells turn into nerve cells, muscle cells, etc.
How are genes regulated?
HOX genes: a series of genes that controls growth/differentiation of an embryo
Mutations in HOX genes lead to severe abnormalites
A certain HOX gene mutation in fruit fly embryos led to the replacement of antennae with legs!!!
(10.1) How big can a cell grow? The larger a cell is, the more demands there
are on its DNA Since DNA does not grow with the cell, there is
only so much to go around!!
The larger a cell is, the harder it is to transport sufficient nutrients and wastes across its cell membrane.
THEREFORE, cells must DIVIDE to remain SMALL in size.
What is surface area to volume ratio?
Sides of a cubic cell: 1cm Surface area = 1cm x 1cm x 6 = 6cm2
Volume = 1cm x 1cm x 1cm = 1cm3
6 to 1 ratio….a lot of area for transport!
Sides of a cubic cell: 3cm Surface area = 3cm x 3cm x 6 = 54cm2
Volume = 3cm x 3cm x 3cm = 27cm3
2 to 1 ratio….NOT a lot of area for transport!
What is the cell cycle?
Interphase: period of cell growth and copying (DNA replication)
Mitosis: period of cell division
At the end of the cycle, one “mother” cell will have split into two identical “daughter” cells!!!
What is the cell cycle?
Steps of the cell cycle…
1) Interphase (G1, S, G2): period of cell growth chromosomes (which hold DNA) are
replicated “sister” chromatids: two copies chromosomes Centromeres: area where “sister” chromatids
are attached
What is the cell cycle?
2) Cell division: mitosis AND cytokinesis
What is the cell cycle?
Steps of mitosis (cell division)…
1) Prophase Chromosomes thicken and become visible Centrioles separate to two opposite sides
of the nucleus Spindle fibers form at centrioles Nucleus dissolves
Why do cells need to divide?
Cells need to divide, because if they get too big… The nucleus cannot control the entire large
cell. The cell membrane cannot bring in enough
materials to keep the entire large cell alive. SO…CELLS NEED TO REMAIN SMALL
IN ORDER TO REMAIN MANAGEABLE!!
What is the cell cycle?
Interphase: period of cell growth and copying (DNA replication)
Mitosis: period of cell division
At the end of the cycle, one “mother” cell will have split into two identical “daughter” cells!!!
What is the cell cycle? 2) Metaphase
Chromosomes line up in the middle of the cell
Centromere of each chromosome is attached to spindle fibers
The centromere is at the middle of the ‘X’ that connects each doubled chromosome.
Each of the 2 copies of the doubled chromosome is called a “sister chromatid.”
What is the cell cycle?
3) Anaphase Centromeres (that join “sister” chromatids)
split “sister” chromatids separate and move to
opposite sides of the cell (pulled by spindle fibers)
Spindle fiber = fishing line Centriole = fishing reel
What is the cell cycle?
4) Telophase Chromosomes tangle at opposite ends of
cell Spindle fibers dissolve Nuclear membrane re-forms
What is the cell cycle?
5) Cytokinesis Cytoplasm divides to create two separate
“daughter” cells with individual nucleus/organelles
Animal cells: pinching Plant cells: cell plate forms (rigid)
(11.4) What is meiosis?
Meiosis: process of reduction division in which the number of chromosomes is cut in half.
What is meiosis?
Humans have 46 chromosomes, 23 from the father and 23 from the mother. These chromosomes are numbered #1-#23 and are arranged in pairs.
Each pair are called HOMOLOGOUS CHROMOSOMES.
They code for the same information, but are just different versions….paternal and maternal!!!
What is meiosis?
Human BODY cells always have 46 chromosomes (23 pairs of homologous chromosomes), and are therefore called DIPLOID cells. Diploid = 2 copies or sets
What is meiosis?
But, human SEX cells (gametes) only have ONE pair, or set, of chromosomes, and are called HAPLOID cells. Haploid = 1 pair or set
MEIOSIS: Haploid sex cells are produced from diploid cells!
What is meiosis? Phases of meiosis… 1) Interphase: growth, DNA replication
2) Meiosis I: VERY similar to mitosis A) Prophase I: each chromosome pairs with its homologous
chromosome…TETRAD, and CROSSING-OVER occurs, where alleles are exchanged between the homologous chromosomes.
B) Metaphase I
C) Anaphase I: spindle fibers pull homologous chromosomes towards opposite sides of cell
D) Telophase I/Cytokinesis
What is meiosis?
(At the end of Meiosis I, there are two haploid cells formed from one diploid cell.)
3) Meiosis II Prophase II, Metaphase II, Anaphase II, Telophase
II, and Cytokinesis all happen just like mitosis.
(At the end of Meiosis II, there are four haploid cells formed from two haploid cells.)
What is meiosis?
Male gametes: sperm/pollen 1 diploid cell makes 4 haploid gametes
Female gametes: eggs 1 diploid cell makes 1 LARGE haploid
gamete and 3 useless “polar bodies” This is due to uneven cell divisions during
meiosis within females!
What is genetics?
Genetics: the study of heredity Heredity– the passing of characteristics
from one generation to the next
How were genetic principles discovered?
Gregor Mendel: Austrian monk that discovered most basic genetic principles
In his experiments, Mendel cross-pollinated different pea plants on his own.
How were genetic principles discovered?
Mendel had true-breeding pea plants in his garden. True-breeding plants: if they were allowed
to self-pollinate, their offspring would be IDENTICAL to themselves
Mendel discovered several important characteristics of genetics…
How were genetic principles discovered?
1) DOMINANCE 7 traits (characteristics) were studied Parents with different variations of each trait
(P) were crossed to form hybrid offspring (F1)
Trait: Seed Shape P (round) x P (wrinkled) F1 was round ROUND was dominant over WRINKLED
How were genetic principles discovered?
Conclusion #1: Each trait was passed from one generation to the next (through chemical factors called GENES).
Conclusion #2: There are usually TWO forms of each gene, and each of these forms is called an ALLELE.
Conclusion #3: Some alleles are DOMINANT and some are RECESSIVE.
How were genetic principles discovered?
2) SEGREGATION What happened to the recessive allele…
did it disappear? NO!!!
Example… Cross P (tall) with P (short) ‘tall’ is dominant, so F1 plants are all tall BUT, then cross an F1 with another F1 and
get 3 tall plants and one short plant…the recessive allele did NOT disappear!
How were genetic principles discovered?
Segregation: the two different alleles for each gene SEPARATE from each other during formation of GAMETES (sex cells).
(11.2) How can we predict the outcomes of genetic crosses?
Punnett square: a diagram that displays results from a genetic cross Assume that each genetic trait has two
alleles Dominant allele = capital letter (T) Recessive allele = lowercase letter (t)
TT: Homozygous dominant tt: Homozygous recessive Tt: Heterozygous
How can we predict the outcomes of genetic crosses?
Phenotype: physical characteristics “the plant is tall”
Genotype: genetic makeup “the plant is homozygous dominant, TT”
(11.3) What is independent assortment?
After Mendel figured out that one allele was DOMINANT over another allele, and that these two alleles SEGREGATE independently into gametes, he had another question….
Does the segregation of one pair of alleles affect the segregation of another pair of alleles?
Does the gene determining seed shape related to the gene determining seed color?
What is independent assortment?
Step 1: Crossed round yellow peas (RRYY) with wrinkled green peas (rryy)
Step 2: Proved that round (R) and yellow (Y) were dominant, since all F1 offspring were… Phenotype: Round and Yellow Genotype: RrYy
What is independent assortment?
Step 3: Cross F1 plant with F1 plant (RrYy x RrYy)
Step 4: Results (F2 generation) produced all possible combinations of offspring RRYY, RRYy, RrYY, RrYy, RRyy, rrYY, rrYy, Rryy, rryy
Seed shape alleles SEGREGATED INDEPENDENTLY from seed color alleles!!!
Principle of Independent Assortment!!!
What are some exceptions to Mendel’s discoveries?
There are exceptions to Mendel’s “genetic principles”!
What are some exceptions to Mendel’s discoveries?
Exception #1: Incomplete Dominance Heterozygous phenotype is halfway in
between the two homozygous phenotypes Red x white = pink!!!
Exception #2: Codominance Both alleles contribute to phenotype
Black x white = black and white spots!
What are some exceptions to Mendel’s discoveries?
Exception #3: Multiple Alleles Many genes have MORE than two alleles
Rabbit coat color (C, c, cch, ch) Human blood type (A, B, O)
Exception #4: Polygenic Traits Traits produced by interaction of more than
one gene Human skin color and height
(14.1) What is a karyotype?
What is a karyotype?
Karyotype: a picture of all 46 human chromosomes arranged within their homologous pairs
Sex chromosomes (pair #23): X and Y (XX = female and XY = male)
Autosomes (pairs #1-#22): the “other” 44 chromosomes in a human
What is a pedigree? Pedigree: chart showing the genetic
relationships within a family
Human Genes
Study blood group genes on p. 344/345 IA and IB
and i are the alleles (3)
Rh+ and Rh- are the alleles for
positive/negative blood type
Most genetic disorders are causes by recessive alleles p. 345 Chart
Human Genes
Cystic fibrosis (CF): caused by a recessive allele on chromosome #7
Sickle cell anemia: caused by a point mutation in a recessive allele on chromosome #11
Sex-linked genes
Sex-linked genes are on X & Y chromosomes Most alleles are found on the X chromosome,
and are called ‘X-linked’
Males are affected by X-linked disorders more often than females because they have only one X chromosome, so if it is defective, they have no “backup” X to cover for the mistakes like females do.
Colorblindness, Hemophilia, Duchenne muscular dystrophy
X-inactivation
In females, it is unhealthy to have both X-chromosomes “turned on” at the same time, so one is always inactivated
If one X is defective, it is always switched “off” In different parts of the body, a different X may be
“on” or “off” X1 may be on in the torso while X2 may be off, but
X2 may be on in the head/neck area while X1 may be off.
Cat example
How many genes are on chromosomes?
There are many genes on autosomes. Chromosomes #21/22 are the smallest
human chromosomes. Combined, they hold at least 770 genes!!
What causes chromosomal disorders?
Chromosomal disorders: result from extra (or missing) chromosomes or parts of chromosomes usually caused by nondisjunction. Nondisjunction: homologous
chromosomes fail to separate during meiosis
DOWN SYNDROME: “Trisomy-21” TURNER’S SYNDROME: X KLINEFELTER’S SYNDROME: XXY
Ch. 13 Overview
Selective breeding: humans CONTROL reproduction of organisms to allow specific traits to be passed to offspring
Dogs…a Chihuahua and a Great Dane are the SAME species, but have been bred in a VERY different manner for 1000s of years
Ch. 13 Overview
Hybridization: crossing (mating) individuals that are NOT similar in order increase the gene pool and bring together the “best of both worlds” GOOD (seedless watermelons)
Inbreeding: crossing (mating) individuals that are similar in order to preserve physical characteristics BAD
Ch. 13 Overview
Inducing mutations: cause mutations on purpose to “see what will happen”…sometimes, it is good!
Ch. 13 Overview
Genetic engineering: making changes in the DNA code of a living thing DNA extraction DNA cutting and DNA
separation Restriction enzymes: cut DNA at specific
points Gel electrophoresis: technique used to
separate DNA based on electric charge and size
Ch. 13 Overview
Recombinant DNA: DNA molecules created by taking a gene from one organism and attaching it to the DNA of a different organism….GENE THERAPY!!!
Polymerase Chain Reaction (PCR): high-speed copying process for DNA
Ch. 13 Overview
Transformation: DNA fragments (or genes) are inserted into the DNA of an existing cell (creating recombinant DNA)
Transgenic organisms: organisms that contain DNA from a different species Human insulin gene inserted into
bacteria…now this bacteria makes human insulin for medical use!!!
Ch. 13 Overview
Transgenic organisms, continued… Transgenic mice have been implanted with
human genes for research 52% of soybeans/25% of corn produced in
U.S. are transgenic
Clone: a population of genetically identical cells produced from a single existing cell
Cloned animals can now be produced
What is the Human Genome Project?
Human Genome Project: effort to analyze the entire human DNA sequence and locate all genes within all chromosomes
Gene Therapy: replacing an absent or defective gene with a gene that works Remove bone marrow, modify all cells, replace it
Ethical issues…how far should science go to alter the basis of life on Earth???????
What is evolution?
Evolution: change over time Charles Darwin: voyaged on the HMS Beagle to
collect evidence for his theory
Darwin found that all species were specifically adapted to their environments. Tortoise & Finch population of the Galapagos
Islands
SEPARATE SPECIES EVOLVED FROM ONE “PARENT” SPECIES!!!!!
What ideas preceded evolution?
Before Darwin, most people believed that living things had been created no more than 2000-3000 years ago.
BUT…old fossils were being discovered that were MILLIONS of years old.
What ideas preceded evolution?
James Hutton: proposed that Earth had to be much older than ~3000 years old
Charles Lyell: proposed that geologic features on Earth change over time…life probably changed as well!
What ideas preceded evolution?
Jean-Baptiste Lamarck: “Use/Disuse Theory”…first ‘evolution-like’ theory If an organism used/did not use a
particular feature in its lifetime, this use/disuse would be passed on to offspring
(If a man was a bodybuilder, his child would be naturally muscular.)
WRONG!!! (but it was an interesting idea)
What ideas preceded evolution? Thomas Malthus: if the human
population grew continuously, we would hit the Earth’s carrying capacity and people would die.
Darwin agreed, and thought… “WHY haven’t plants/animals grown
continuously over time? WHAT causes some to survive and others to die? HMMMM….
Darwin’s Evidence of Evolution
On the Origin of Species: Darwin’s book about evolution (1859) Topics included…
NATURAL SELECTION PHYSICAL EVIDENCE FOR EVOLUTION
Darwin’s Evidence of Evolution
Artificial selection: nature provides genetic variation and humans select desirable traits for further mating…crops/livestock were undergoing an “artificial evolution”!!!
Struggle for existence: animals survive that are faster, stronger, better camouflaged, better protected, etc. than those who are slower, weaker, etc.
Darwin’s Evidence of Evolution
Survival of the fittest: individuals with adaptations that enable fitness survive and reproduce most successfully
Also called “natural selection”
Adaptation = an inherited characteristic that increases an organism’s chances of survival
Fitness = ability of an organism to survive in its environment
Darwin’s Evidence of Evolution
OVER TIME, NATURAL SELECTION RESULTS IN CHANGES IN THE INHERITED CHARACTERISTICS (the genes) OF A POPULATION!!!
Descent with modification: each species in existence today came from other species over time…they just changed in some way(s) EVERYTHING came from a SINGLE organism
(COMMON DESCENT)
Darwin’s Evidence of Evolution
EVIDENCE: 1) Fossils: a person can “see” an
organism evolving through history by looking at fossils of different ages
2) Embryology: early embryos of many animals look almost EXACTLY the same!
Darwin’s Evidence of Evolution
3) Homologous body structures: organs or limbs differ in form or function, but contain SAME basic structures
Turtle leg, alligator leg, bird wing, human finger all have similar bone structure and likely all came from a specific ancient fish fin!
Homologous = related by evolution & genes {HUMAN ARM & DOLPHIN FIN}
Analogous = look the same, but NOT related by evolution & genes {DOLPHIN FIN & SWORDFISH FIN}
Evolution of Populations
(This chapter connects evolution with genetics….it is all about what Darwin DIDN’T know!!!)
Genetic variation: all organisms have many different allele combinations for their genes within an entire population
Evolution of Populations
Gene pool: all genes and alleles that are present in a population
Relative frequency: # of times that an allele occurs in a gene pool for a single gene
EVOLUTION = ANY CHANGE IN THE RELATIVE FREQUENCY OF ALLELES IN A POPULATION
Evolution of Populations
How do genes become “varied”? 1) Mutations 2) Gene shuffling….crossing over and
sperm-egg combinations!
Evolution of Populations
Natural selection works differently on single-gene traits than it does on polygenic traits.
Single-gene traits: natural selection can “select for” the dominant or recessive allele, and the relative frequency may change
Evolution of Populations
Polygenic traits: Directional selection
Organisms at ONE END of the curve have highest fitness
Stabilizing selection Organisms near CENTER of the curve have
highest fitness Disruptive selection
Organisms at BOTH ENDS of the curve have highest fitness
Evolution of Populations
Natural selection is NOT the only mechanism of evolution…GENETIC DRIFT is another mechanism.
Genetic drift: if a CHANCE OCCURRENCE causes change in a population…has nothing to do with “survival of the fittest” Only occurs in small populations
Evolution of Populations
Hardy-Weinberg Principle: allele frequencies in a population will remain constant (at “genetic equilibrium”) if 5 conditions are met…
1) Random mating 2) Large population 3) No immigration or emigration 4) No mutations 5) No natural selection IF any one of these conditions is NOT met,
then EVOLUTION will occur!!
What is speciation?
Speciation: formation of a new species
Reproductive isolation: two different species CANNOT successfully mate with each other Behavioral: different courtship rituals (BIRD
MATING DANCES OR SONGS) Geographic: separated by rivers, mountains
(GRAND CANYON SQUIRRELS) Temporal: different mating seasons (FLOWERS)
How does natural selection work in nature?
Darwin’s “process” of evolution: Founding Separation of populations Different adaptations Gene pool
changes Reproductive isolation occurs Competition REPEAT
(18.1) How are organisms classified?
Taxonomy: study of the logical organization of all living things
Binomial nomenclature: two-word name Genus name (capitalized) Species name (NOT capitalized)
Homo sapiens
How are organisms classified?
Carolus Linnaeus: Swedish scientist who classified organisms in a 8-level system Domain Kingdom Phylum Class Order Family Genus Species
(18.2) How are organisms classified?
Phylogeny: study of evolutionary relationships among organisms
Cladogram: diagram that shows evolutionary relationships among organisms Species sharing the same “fork” or that
reside close together on a cladogram are closely related
How are organisms classified?
Similarities in DNA sequence is an excellent way to determine evolutionary relationships among organisms.
(18.3) How are organisms classified?
Two different classification systems… 1) Domain system
Bacteria, Archaea, Eukarya (3) 2) Kingdom system
Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia (6)
How are organisms classified?
Dichotomous key: method of using a series of “yes” and “no” questions to classify large groups of organisms and make identifications of specific organisms
Plant Overview
Plant Overview
Stamen: male ‘parts’ Anther: tip that makes/releases pollen Filament: stalk that supports the anther
Carpel (Pistil): female ‘parts’ Stigma: sticky tip Style: stalk leading from stigma to ovary Ovary: chamber containing ovules Ovule: female egg
Plant Overview
Sepal: outermost, leafy flower parts Petal: brightly colored, inner flower parts
ATTRACT POLLINATORS!! Pollination occurs via…
Wind Animals
Plant Overview
After pollination & fertilization, a seed is formed. Then…
1) Dispersal: seeds spread by wind, water, animals
2) Dormancy: seeds “sleep” until environment is ideal for growth
FIRE CHERRY: SEEDS DO NOT GERMINATE UNTIL THERE IS A FOREST FIRE
3) Germination: early growth of plant…eruption from seed
Plant Overview
Plant Hormones:
1) Auxins: regulate stem growth 2) Cytokinins: regulate root growth 3) Gibberellins: produce huge size in
stems and fruit 4) Ethylene: stimulates fruits to ripen
Plant Overview
Plant responses:
1) Phototropism: plants grow toward light 2) Gravitropism: plants grow AGAINST
gravity
Plant Overview
Plant adaptations:
1) Salt: excess salt is released through leaves and then washed off by rain
2) Desert: large root systems, small leaves, thick, water-storing stems
3) Low nutrient levels: eat insects / parasitic plants
4) Defense: make toxic substances to kill ‘predators’
Animal Behavior (Ch. 33)
Behavior: anything an animal does in response to a stimulus INNATE BEHAVIOR LEARNED BEHAVIOR COMMUNICATION Stimulus: an environmental change that
directly influences the activity of an organism
Animal Behavior (Ch. 33)
Innate behavior: behavior patterns that are inherited by genes Behaviors lead to high fitness! 3 major types
Animal Behavior (Ch. 33)
Type 1: Fixed-action pattern Unchangeable behavior pattern Toad senses motion pinpoints motion
extends tongue to capture prey retracts tongue
Animal Behavior (Ch. 33)
Type 2: Automatic response Reflex: automatic response to stimulus
with no conscious control (jumping b/c of fire alarm)
Fight-or-Flight: mobilizes body for danger Controlled by hormones Adrenaline—increased heart rate, sweaty
palms, increased muscle sensitivity
Animal Behavior (Ch. 33)
Type 3: Instinct A) Courtship (mating dance) B) Territoriality (protection of breeding
ground, feeding ground, and sexual partners)
Wolf urine C) Dominance hierarchy (aggression vs.
submission) “Pecking order” in chickens
Animal Behavior (Ch. 33)
D) Circadian Rhythms (24-hour light/dark cycle keeps us awake during the day and sleepy at night) Reversed for nocturnal organisms
E) Migration (travelling for food/mating reasons Usually associated with weather or day
length Pilot Mtn. – Hawk example
Animal Behavior (Ch. 33)
F) Hibernation (energy conservation) Bear hibernates in winter
G) Estivation (energy conservation in areas where seasons don’t change) Desert snake estivates during periods of
low food sources
Animal Behavior (Ch. 33)
Learned behavior: behavior changes through practice or experience Increased brain power = Increased
capability for learned behavior 5 major types
Animal Behavior (Ch. 33) Type 1: Habituation
Animal gets “used to” a stimulus. No reward or punishment is involved. Ex: A horse gets used to cars driving by the field.
Type 2: Imprinting Babies recognize a “mother” during specific window
of youth. It is possible for one species of “mother” to be
imprinted on another species of baby.
Animal Behavior (Ch. 33)
Type 3: Trial & Error Improve quality of behavior-related product
with each trial. Bird nests…first try—glass bottles; fifth try
—twigs and grass Type 4: Classical Conditioning
“Pavlov’s response”…learn by association Bell rings food is presented….bell is
associated with food
Animal Behavior (Ch. 33)
Type 5: Insight Applying previous experience to a new
situation Mathematics & other “higher thinking” Chimp & 2-pole example
Animal Behavior (Ch. 33)
Communication: 1) Sound (bird song) 2) Sight (mating dance) 3) Touch (human approval…”pat on the
back”) 4) Smell (ant trails leading back to nest)
PHEROMONES 5) Language (use of symbols to express
ideas)