AP BIO EXAM REVIEW
UNIT 1 - Chemistry of Life
Hydrogen Bonds in Water
Properties of water
Water dissolves polar and charged molecules
Water is cohesive and adhesive
Polar because bent shape and partial negative oxygen/partially positive hydrogen
Water has high heat capacity - it takes a lot of energy to raise the temperature
Water has a high heat of vaporization - water can be used to cool people off and converted to steam
Molecules in ice are further apart which is why it is less dense than liquid water
Water attracts to each other using hydrogen bonds
Attracts to other polar molecules and ions
Hydrophilic - molecules attracted to water
Hydrophobic - molecules not attracted to water
Cohesion and adhesion of water
Cohesion - attraction between molecules of the same kind
Cohesive forces cause surface tension
Allows water to support itself and create droplets because it's surrounded by air so it creates stronger bonds to itself
Adhesion - attraction between molecules of different kinds
Water is especially adhesive with molecules with a positive or negative charge
Water can “climb” through glass tubes - called capillary action - because the water is adhesive to the glass
Matter, atoms, and Elements
Matter - anything that occupies space and has mass
Structure of an atom
Nucleus - in the center with protons and neutrons
Electrons surround it
Carbon and Hydrocarbons
Macromolecules - called organic molecules which means they contain carbon albums
Carbon bonds are strong (covalent bonds) - so carbon is usually the backbone of macromolecules
Hydrocarbons - molecules consisted out of hydrogen and carbon only
They store a lot of energy
Chemical bonds
Ionic bonds - when atoms lose or gain electrons - form ions/ionic bonds
Cations - positive ions bc LOSE elections
Anions - negative ions bc GAIN electrons
Covalent bonds - when atoms share electrons
Key way that DNA/proteins are structured
More electrons shared, stronger the bond will be
Hydrogen bonds - polar covalent bond containing hydrogen
Hydrogen is slightly positive so it will be attracted to slightly negative
Macromolecules
Polymers - long chains made up of monomers
Can be made of different monomers
Ex. proteins made of 20 diff amino acids
Ex. dna made of 4 nucleotides
Carbohydrates, nucleic acids, and proteins are macromolecules
Phosphorus makes nucleic acids and lipids !!!
Dehydration synthesis - how large molecules assemble
One monomer hydrogen bonds to another
Covalent bond
Require energy to do reaction
Hydrolysis - when polymers are broken down into monomers
When split one monomer gains a H group and one gains a OH- groups
Releases energy
Carbohydrates
Carbohydrates - molecules made out of carbon, hydrogen, and oxygen
Monosaccharides - simple sugars - glucose
Sugars are ring shaped
Disaccharides - when two monosaccharides are join together because of dehydration synthesis
Form hydrogen bond and release water
Polysaccharides - long chain of monosaccharides
Starch - mixture of two polysaccharides (made of glucose)
Cellulose - what cell walls are made of
Proteins
Primary structure
Linear sequence of amino acids
Secondary structure
Forms a coil - alpha helix
Forms a zig zag - beta pleated sheets
Shapes based on R- groups
Tertiary structure
Can have alpha and beta chains within
Bonds between R groups by Hydrogen, Ionic bonds, Disulfide bridges, Hydrophobic interactions
Quaternary structure
Same bonds as tertiary structure but bonds between entire peptide chains rather than R groups
Unit 2 - Cell Structure and Function
All cells have genomes and ribosomes
Ribosomes
Synthesize proteins according to mRNA sequence
mRNA comes from genome
2 subunits
Made of rRna
Endoplasmic reticulum
Network of membrane tubules in cytoplasm
Rough ER
Has ribosomes attached to it
Therefore carries out protein synthesis
Packages newly synthesized proteins for export from the cell
Smooth ER
Does NOT have ribosomes
Lipid synthesis
Golgi complex
Membrane bound sacs
Folding and chemical modification of newly synthesized proteins
Packaging proteins
Mitochondria
Outer membrane - smooth
Inner membrane - folded
Capture energy from macromolecules (carbs, glucose)
Krebs cycle in the matrix
ETC and atp synthase in inner membrane
Lysosomes
Contain hydrolytic enzymes
Used to digest macromolecules or damaged cells
Recycle materials
Forced cell death
Vacuoles
Storage of water - for turgor pressure
Turgor pressure - caused by water pushing up against plasma membrane and cell wall
Release of waste products
Chloroplasts
Double outer membrane
Capturing energy and producing glucose
Thylakoid - membrane compartments organized in stacks called grana
Chlorophyll pigments are in photosystems which are in the thylakoid membrane
Light reactions
Stroma - fluid between inner chloroplast membrane and outside thylakoids
Calvin cycle
Plasma membrane
Provides a boundary between the interior of the cell and outside environment
Control the transport of materials in and out of the cell
Phospholipids
Hydrophilic phosphate head
Hydrophobic fatty acid tail (nonpolar)
Form a bilayer (tails interact with each other and heads interact with aqueous outside and inside)
Embedded proteins
Peripheral proteins - loosely bound to surface of membrane
Hydrophilic - interact with the polar heads
Integral proteins - span the membrane
Hydrophilic - charged side groups
Hydrophobic - nonpolar middle groups
Membrane protein functions
Transport
Cell to cell recognition
Enzymatic activity
Signal transduction
Intercellular joining
Attachment for extracellular matrix or cytoskeleton
Fluid mosaic - mosaic of proteins in fluid bilayer
Held by hydrophobic interactions (weaker than covalent bonds)
Proteins and lipids shift/flow across membrane
Cholesterol - steroid randomly wedged between phospholipids
Regulate bilayer fluidity under certain environmental conditions
Carbohydrates and lipids on membrane that act as markers
Glycoproteins
One or more carbohydrates attached to membrane
Glycolipids
Lipid with one or more carbohydrate attached
Membrane permeability
Small nonpolar molecules pass freely
N2, O2, CO2
Hydrophilic molecules (large nonpolar molecules and ions) can not pass freely through
Transport proteins
Channel proteins - tunnel spanning the membrane that allows target molecules to go through
Carrier proteins - Spans the membrane and changes shape to move target molecules from one side to another
Cell wall
structural boundary
Protects and maintains shape of cell
Prevents cellular rupture when turgor pressure is high
Permeable barrier
Plasmodesmata - small holes between plant cells that allow transfer of nutrients and ions
Made of cellulose in plant cells (polysaccharide)
Facilitated diffusion
Movement of molecules from high concentration to low concentration through transport proteins
Large and small polar molecules
Large quantities of water through aquaporins
Charged ions require channel proteins
Active transport
Moves molecules against their concentration gradient from low to high
Require pumps and use ATP
Water Potential
Water potential measures the tendency of water to move by osmosis
Calculated from pressure potential and solute potential
Moves from area of high water potential to low water potential
Values of water potential can be positive or negative or zero
The more negative the water potential is, the more likely water will move into that area
Water potential of pure water has a value of zero
There's no solutes
No pressure bc in open container
Osmoregulation - allows organisms to control internal solute composition and water potential
Increase solute in water = increase solute potential and decrease water potential
Increase water portnation = increase pressure potential
Solute potential
Ionization constant (ex. Sucrose = 1)
C = molar concentration (mmoles)
R = pressure constant
T = temperature in celsius + 273 = Kelvin
More solutes = negative solute potential
Diffusion - movement of molecules from high to low concentration
Facilitated diffusion = movement of molecules from high to low concentration through channel proteins
Movement of large molecules in and out of cell
Endocytosis - forming vesicles derived from plasma membrane
Phagocytosis
Pinocytosis
Receptor mediated endocytosis
Exocytosis - internal vesicles fuse with membrane and put stuff out of the cell
Compartmentalization
All cells have a plasma membrane - maintain different internal and external excitement
eukaryotic cells have additional membrane bound organelles that compartmentalize the cell
Allow for metabolic process and enzymatic processes to be at the same time = increased efficiency
Example - lysosomes need to function in an acidic environment
Can maintain acidic inside while having more neutral outside environment
Unit 3 - Cellular Energetics
Enzyme Structure
Enzymes - catalysts that speed up chemical reactions
Proteins - tertiary shape
Have an active site that is very particular
Substrate that interacts with enzymes specific active site
The active site can be altered to fit the substrate
Reusable - not chemically changed by reaction
Facilitate synthesis or digestion reaction
Enzyme names indicate the substrate or chemical reaction involved
End in -ase
Ex. sucrase is enzyme that digests sucrose
Enzyme Catalysis
All biochemical reactions require starting energy - ACTIVATION ENERGY
Some reactions result in net release of energy and some with a net absorption
Reactions w/net release require LESS activation energy
Enzymes lower activation energy required - accelerating rate of reaction
A controlled experiment is an scientific investigation - w/2 types of tests
Control group
Generates data under conditions with no treatment
Generates data under normal/unchanged conscious
Baseline data
Experimental groups
Data under abnormal conditions
Under treated/manufactured conditions
Compared with control test results to see impacts of treatment
Control groups
Negative control
Not exposed to experimental treatment or ANY treatment with an effect
Positive control
Exposed to treatment with a known effect
Not exposed to experimental treatment
Enzymes have specific conditions for maximum function
Changing temp, ion concentration will interfere with the bonds (hydrogen and ionic) and change the shape of the active site
Enzyme can be denatured (function doesn't happen anymore)
Temperature effect on enzyme
Optimum temperature - more kinetic energy increases molecular motion and increases the chance that enzyme bond with substrate
At too high temperature it will denature
Reversible denaturation - restoration of optimal conditions resorts the enzymes optimal shape
Irreversible denaturation - enzymes shape permanently changed and catalytic ability is destroyed
Substrate concentration effect on enzyme activity
Low concentration - probability of enzyme bumping into substrate is low and product produced at low rate
As substrate concentration inc, collision and rxn rate increase
Saturation point - when all the active sites of the enzymes are taken up
Competitive v noncompetitive inhibition
Competitive: foreign molecule that's not the enzymes substrate blocks the active site and inhibits the rate of reaction
Noncompetitive: foreign molecule binds away from the active side called allosteric site which has a ripple effect through the protein which causes a change in shep of the active site
Metabolic pathway
Linked series of enzyme catalyzed chemical reactions within a cell
Example:
1, 2, 3, are enzymes
a is reactant
b and c are intermediate
d is the product
Examples are glycolysis, krebs cycle, etc
Can be linear (glycolysis) or circular (calvin/krebs)
Autotrophic - organisms that produce their own food
Photoautotrophs (plants, cyanobacteria) - use light energy to create organic components to survive through photosynthesis
Chemoautotrophs (bacteria) use the energy from chemosynthesis which oxidizes inorganic substances (iron, sulfur)
Heterotroph 0 capture energy present in organic compounds produced by other organisms
Consumers, decomposers
Metabolizing the organic compounds in those that they eat or absorb
Exergonic - release energy and increase entropy
Example - burning stuff releases chaotic chemicals
Cell respiration and hydrolysis
Endergonic - require energy and decrease entropy
Photosynthesis or any dehydration synthesis
Structure + function of ATP
Structure - 5 carbon sugar ribose, nitrogenous base (adenine), 3 phosphate groups
Function - power work within cells (every cell makes its own atp)
Storing energy - cells take energy from food during cellular respiration and combine with ADP and phosphate groups to make ATP
Release energy for work - cells remove a phosphate group creating ADP + P
Energy coupling - linking an exergonic reaction to an endergonic one
Drives the endergonic reaction forward
Ex: cell respiration (exergonic rxn) drives formation of ATP from ADP and P (endergonic)
Ex: exergonic ATP to ADP and P makes stuff like active transport possible
Photosynthesis
Using light energy - photoautotrophs use CO2 and H20 to create carbohydrates - O2 released
Source of biomass in every food chain
Endergonic rxn - takes two low energy inputs and converts them into high energy products
Reduces entropy (12 molecules on reactant side converted into 7 on the product side)
Co2 gas created into a solid object
Light Reactions - converts light energy into chemical energy (ATP and NADPH)
The Calvin Cycle - converts chemical energy in NADPH and ATP into carbohydrates
Fixes carbon dioxide - low energy gas into high energy sugars
Chlorophyll - pigment that absorbs light energy
Absorption spectrum - shows the amount of light absorbed at different wavelengths
Chlorophyll has two forms, one that absorbs blue and red, one that DOES NOT ABSORB GREEN (plants r green bc green light bounces off)
Action spectrum - shows how different light wavelengths drive photosynthesis (blue and red does most while green doesn't)
Chloroplast - found in plant cells
Has outer and inner membrane
Two membranes example of evolution of the membranes from a prokaryotic cell
Has DNA and ribosomes
Has thylakoids - membrane bound sac
Contain chlorophyll for light reaction
Organized in grana stacks
Stroma - cytoplasm of the chloroplast
DNA, ribosomes,
Where calvin cycle
Light Reactions - occurs in thylakoids
Outputs - o2 is waste product
Inputs - light and water
NADP+ and ADP + P (from the calvin cycle)
Photosystems - proteins imbedded with chlorophyll
Convert light energy into a flow of electrons
Splits water molecules (photosystem 2)
Photosystem 2 comes before photosystem 1
A and d - light energy
Electron pathway - i, b, e, f
Proton pumps - c
Protons from stroma to thylakoid space
Photoexcitation of chlorophyll in PSII begins a flow of electrons along an ETC in the thylakoid membrane
ETC powers the proton pumps from the stroma to thylakoid space
Result - chemiosmotic gradient powers ATP synthase as protons diffuse from the thylakoid space back to the stroma via ATP synthase
PS II - water splitting complex
Splits water apart (CREATES OXYGEN) and also creates protons for the gradient
Calvin Cycle
Photoexcitation of chlorophylls in photosystem 1
Creates flow of electrons of ETC of PS I
Electrons flow to NADP+ Reductase which NADP+->NADPH
Bc during calvin cycle NADPH to reduce CO2 to carbohydrates
The Calvin Cycle
Carbon fixation phase
CO2 Is combined with RuBP
Reaction is catalyzed by RuBisCo
Six carbon product immediately dissociates into two 3 carbon molecule
Energy investment and harvest phase
Starts with 2 three carbon molecules
That 3 carbon product is reduced and phosphorylated
ATP contributes a P to the molecule
NADPH donates an electron to the molecule
End with G3P
Regeneration of RuBP
Remaining 5 G3P are rearranged into three 5-carbon molecules
Phosphorylation occurs
RuBP is a substrate that starts the whole calvin cycle
Pay attention to amount of carbon atoms in each phase
Starts with 3 RuBP (5 carbons each) combined with 3 carbon dioxide which is 18 Carbons
At the end of carbon fixation - 6 3 carbon molecules (18 carbon)
Duringenergy investment - 6 molecules of G3P
One G3P gets pulled out and is available to make carbohydrates
During regeneration of RuBP - arranged into 3 five carbon RuBP
Cellular respiration
Exergonic reaction - release energy and creates disorder
Takes organized glucose and converts to gasses
Glycolysis occurs in the cytoplasm and the link reaction brings the energy into the mitochondria
Krebs cycle where the matrix occur
oxidative phosphorylation - in the intermembrane space
Glycolysis
Energy in glucose generates NADH some ATP
End product ends with 3-carbon pyruvic acid
Cytoplasm - does not require oxygen - aerobic - 3 phases
1. Investment - enzymes phosphorylate glucose
Take phosphate from ATP
2. Cleavage - intermediate fructose is split into 2 G3P
3. Harvest - G3P is oxidized (lose energy) and NAD+ is reduced to NADH
Enzymes phosphorylate two ATPs (from G3P)
Net yield of glycolysis is 2
It's 4 but two get used at the beginning.
Get 2 pyruvate from
Link Reaction
Brings pyruvate into mitochondria matrix and converts it to Acetyl CoA (2 carbons)
generates NADH
Releases one CO2 (one carbon)
1./3 of the co2 released
Other enzymes oxidize the resulting two-carbon molecule (acetyl) reduces NAD+ to NADH
Enzymes take acetyl and attach it to coenzyme A = acetyl COA -> start of krebs cycle
Krebs cycle
oxidizes acetyl CoA - to produce 3NADH, 1 ATP, 1 FADH2 and releases 2CO2
In mitochondrial matrix
Starts w/enzymes taking Acetyl CoA to become citric acid
Enzymes start to oxidize citric acid (loss of electrons)
Electrons go to NAD+ -> NADH
Other enzymes power substrate level phosphorylation of ADP and P into ATP
For each acetyl CoA that enters cycle - one ATP, one FADH, and 3 NADH are generated
CO2 us waste product
Electron transport chain - ETC and oxidative phosphorylation
Oxidises NADH and FADH2 to create electron flow to power phosphorylation of ADP to ATP (ONE)
Those electrons go through ETC in mitochondrial inner membrane
Some ETC proteins are proton pumps that pump protons into matrix
Active transport that gets energy from the electrons
Creates electrochemical gradient
Oxygen acts as the final electron acceptor
Bc so electronegative that it pulls electrons down
Protons in intermembrane space go through ATP synthase
As protons diffuse through - energy is used to create ATP
Anaerobic v Aerobic respiration
Aerobic - oxygen is required
Glycolysis + Link + krebs + ETC = 32 ATP for every glucose molecule
Most ATP generated in mitochondria
Anaerobic respiration (when o2 isn't present, is insufficient, or when organism does not have enzymes to do aerobic)
Glycolysis is the key part followed by fermentation = 2 ATP
Occurs in cytoplasm
Fermentation
Glycolysis followed by reactions that generate NADh
Why: when aerobic isn't working but you still need to work, you can still get energy
alcoholic fermentation v lactic acid fermentation
Ethanol fermentation - in yeast
Enzymes remove C02 from pyruvic acid
Produces ethanol and NADh oxidized to NAD+
Allows glycolysis to continue
lactic acid fermentation
Occurs in muscle during anaerobic condition
Pyruvate reduced to lactic acid and NADH is oxidized to NAD+
UNIT 4 - Cell Communication and Cell Cycle
Communication through direct contact
Cells of multicellular organisms maintain physical contact with one another
Unicellular organisms usually live in colonies that are in physical contact with other organisms in that colony
Cells can send chemical signals directly into adjacent cells
Cell membrane and cell wall mods allow for communication to occur between adjacent cells
Communication
Cells use chemical signals for short and long distances
The cell receiving the signal is the target cell
Short distance
Cells send out local signals
Target cell is within short distance
Used to communicate with cells of the same type
Long distance
Target cell in diff area as the cell emitting the singla
Ex signal from head to stomach
Signal travels larger distance to reach target cells
Uses signal cells of different types
Example - neurotransmitters communicate using local regulators
Exocytotic vesicles release signals
Signal travels short distance between gap
Signal attach to target cell and cause response
Signal transduction pathways (STP)
STP link signal reception with cellular responses
3 steps of cell communication are reception, transduction, and response
Reception: detection of signal molecule coming from outside of the cell
Transduction: convert signal to a form that can bring about a cellular response
Response: specific cell response to the signal molecule
STP include protein modification and phosphorylation cascades
Regulate protein synthesis by turning on and off genes in nucleus
Regulate activity of proteins in cytoplasm
Cascades of molecular ineracts relay signals from receptors to molecules
Phosphorylation cascades - enhance and amplify signal
Signaling
Begins with recognition of chemical messenger (ligand) by a receptor
Ligand binding domain of a receptor recognizes specific chemical messenger which is a specific one to one relation
G-protein coupled receptors
Hormone binds to receptor which converts GDP to GTP which goes through adenylate cycle which converts ATP to cAMP which activates protein kinase
Cascades - relay signals from receptors to target cells - amplifying incoming signals (cell growth, gene expression)
After ligand binds, domain of receptor changes shape initiation transduction of signal
Second messengers (cAMP) relay the message
Takeaways:
Signal transduction pathway is the binding of signaling molecules to receptors on cell surface that trigger events inside the cell that invoke a response
Cells use signal transduction with a cellular response (growth, gene expression)
Signal transduction pathway begins with a ligand bonding to external receptor
Role of protein modification in STP is to change shape due to ligand bonding
Phosphorylation cascade is a signaling pathway where one enzymes phosphorylates another causing an amplification of the pathway
signal transduction pathways influence how a cell responds to its environment
Environment is not static - organisms always need to regulate pathways to respond to changes
Ability to respond to stimuli is necessary for survival
Example
Epinephrine is ligand that bonds to signaling molecule
It activates the G protein
GTP active
G protein activates adenylyl cyclase which converts ATP to cAMP
cAMP activates protein kinase A which leads to the response (glycogen breakdown)
Signal transduction results in changes in gene expression and cell function
Pathways can target gene expression/amount of protein produced
Changes in protein taupe can be a phenotype change
Apoptosis can be response of signal transduction
Changes in signal transduction pathways
Changes in signal transduction pathways alter cellular response
Mutations in any domain of receptor protein effects the rest of the transductions pathway
Chemicals that interfere with the pathway may inhibit or activate the pathway
Feedback mechanisms
Helps organisms to maintain internal homeostasis and respond to environmental changes
Homeostasis - maintenance of stable internal environment
Processes that maintain homeostasis by increasing or decreasing response to cellular event
Negative feedback - maintain homeostasis for particular cell condition
If process disrupted, negative feedback helps it return to homeostasis
Positive feedback - amplify responses in organisms
A variable initiates a response to move further away from homeostasis
Amilpfy that stimulus which creates an entire system change
Example: fruit ripening
When one apple ripens, it releases gas that is detected by other apples
Other apples start to ripen and m0re gas is released
RIPENING APPLES IS MOVING FURTHER FROM HOMEOSTASIS
The cell cycle - series of events for growth and reproduction of cells
Interphase - growth and preparation for cell division
G1 - cell growth
S phase - copies of DNA are made
G2 - cytoplasmic components are doubled - ready for division
mitosis - division of nucleus
Can be asexual reproduction for some organisms
Process that splits into two daughter cells with identical genomes identical to parent cell
Cytokinesis - split cell
Equal split of cytoplasm to daughter cells
Come cells enter G0 where cell division no longer occurs
Can re enter cycle with appropriate signal
Phases of mitosis
Prophase
Nuclear envelope begins to disappear
DNA coils into visible chromosomes (chromatid)
Fibers begin to move chromosomes to middle of cell
Metaphase
Fibers aligned double chromosomes across cell
Anaphase
Fibers separate double chromosomes into single chromosomes
Separated at centromere
Chromatids migrate to opposite sides of the cell
Telophase
Nuclear envelope reappears and 2 separate nuclei
Each nucleus contains complete genome
Chromosomes begin to uncoil
Cytokinesis
Separate cell into two daughter cells (cell membrane forms)
Regulation of the cell cycle
Regulated through checkpoints
G1 checkpoint
At the end of the G1 phase
Cell size, nutrient, growth factor, DNA damage check
G2 checkpoint
DNA replication check
DNA damage check
M-Spindle checkpoint
After metaphase
Making sure fibers attached to chromosomes accurately so it splits correctly
Cyclins
Group of related proteins associated with specific phases of the cell cycle
Concentrations can fluctuate depending on cell activity
Promote cell cycle progression
Degraded to inhibit cell cycle progressing
Used to activate cyclin dependent kinases
Cyclin dependent kinases (enzymes)
Requires cyclin binding for activation
Phothotolate substrate and promote cell cycle
Disruptions in cell cycle that lead to cancer/apoptosis
A cell with a genetic alteration/mutation may singal to go through apoptosis
Genetic alteration where cells skip past checkpoints and just continue to divide -> cancer
UNIT 5 - Heredity
Meiosis
Formation of haploid gamete
Diploid
2 full sets of pairs of chromosomes
Chromosomes differ in size shape etc
Cell contains one set from each parent
Body cells are diploid
Haploid
Contain one set of chromosomes
Gametes - sex cells
2 haploid cells come together to produce a diploid cell
Diploid parent creates 4 haploid/daughter sex cells
Two phases of meiosis - meiosis 1 and 2
Meiosis I
Prophase I
Nuclear envelope disappear
Fibers form
Dna coils and duplicated chromosomes are sister chromatids
Double chromosomes pair up
While pair up, chromatids exchange information by crossing over
Metaphase I
Double chromosomes remain in pairs
Fibers allison them across center of cell
Anaphase 1
Fibers separate chromosome pairs
Chromosomes move to opposite sides
Telophase I
Nuclear envelope reappears and 2 separate nuclei
Each nucleus has one double chromosome
Nucleus only contains half of the total info that parent had
But still double chromosomes
After cytokinesis - two HAPLOID daughter cells
Meiosis II
THIS IS EXACTLY LIKE MITOSIS
Mitosis v meiosis
Both
Nucleus disappear
Dna -> chromatids
Align in center + fibers separate
Nuclear envelope reappear
Cytokinesis
Different
Mitosis - goal is to make 2 daughter cells while meiosis it creates 4 haploid daughter cells diff from parent cell
Meiosis and genetic diversity
Meiosis results in 4 genetically different gametes
CROSSING OVER
Occurs in prophase I
Nonsister chromatids of double homologous chromosomes exchange segments/genes
Recombinant chromatids -> genetic diversity
Random assortment of chromosomes
Order of homologous pairs during meta I effects which chromosomes end up in each gamete
Fertilization of gametes increase variation
During fertilization, info from each parent contributes
One gamete from each parent to form diploid offspring
Fertilization is random and any gamete can become the genome of the offspring
Continuity of life
Heritable information provides for continuity of life
Nucleic acids (DNA and RNA) carries genetic information in their order
That genetic info is transferred to other cells during division
Transmission of genetic info from one gen to another = continuity of life
Shared, conserved processes and features → common ancestry
Genetic code is shared by ALL living systems
All organisms use nucleic acids to store genetic information
All organisms have ribosomes to synthesize proteins based on nucleic acid sequences
Core metabolic pathways are conserved across all domains of life
Ex. cell respiration used by all organisms
Glycolysis is in anaerobic and aerobic respiration
Mendailian genetics
Mendel's laws - describe inheritance of genes on diff chromosomes
A gene is unit of heredity coding for trait
Can be transferred through generations
Trait - characteristic of gene
Allele - specific variation of genes
Alleles from each parent
Organisms can inherit different alleles for the same genes
Dominant allele - its the trait that is shown
Recessive allele - only shown when dominant allele isn't present
Genotype - combination of of inherited alleles
Homozygous - 2 of the same alleles
Heterozygous - two different alleles
Phenotype - physical result of genotype
Law of segregation
Chromosomes carry alleles
Homologous chromosomes carry alleles for the same trait
The allele could be different
When chromosomes separate during meiosis - alleles are also separated
Example: mendel's experiments = specific crosses
P generation - homozygous dominant crossed w/homozygous recessive
The F1 generation all ended up with purple flowers
F1 generation - he crossed two heterozygous plants
F2 generation ended up having 3 purple and one white
Reappearance of white flower - evidence of law of segregation
Recessive alleles from each parent packaged into diff gametes
Law of independent assortment
Two or more genes assort independently of each other
One trait does not automatically have to be inherited with another trait
Alleles for separate traits can be packaged into every possible combination of gametes
Crosses
Monohybrid cross - examination of how one trait is inherited
Two possible phenotypes (R and r)
Three possible genotypes (RR, Rr, and rr)
Dihybrid cross - examination of how two traits are inherited
Punnett squares - outcomes of cross
Pedigrees - visual of representation tracing history of trait through generations
Predicts patterns of inheritance
Helps to identify types of inheritance
Circles - females
Squares - males
Shaded shapes - individuals affected
Chi squared hypothesis testing
Hypothesis testing - reject/fail to reject hypothesis
Determines if differences in numerical data are due to the independent variable or by chance
2 types of hypothesis
Null Hypothesis - states there is no difference between the two groups of data in investigation
Alternative hypothesis - observed results are due to non random results
Chi squared goodness of fit test
Used to determine if there's significant relationship between two groups of data
Compared observed outcomes to expected outcomes
Steps to chi squared test
Establish question
Determine null hypothesis
Determine alternative hypothesis
Count observed valued
Determine expected values
Calculate chi squared
Calculate degrees of freedom
Use p value
Compare chi squared value to critical value and draw conclusion
Nonmendalian genetics
Patterns of inheritance do not follow rations predicted
Genes that are adjacent and close together on the same chromosome that are inherited together are linked genes
Traits determined by genes on sex chromosomes are sex linked traits
Linked genes
Typically inherited together
Less likely to be separated during meiosis
Probability that genetically linked genes will segregate as a unit can be used to calculate the map distance between them
Map distance
Tells you how close a pair of linked genes are
Determined by how frequently a pair of genes participates in a crossover event
Linked genes have recombination frequency of less than 50%
Ex. if a pair of linked genes have recombination frequency of 30% (they are separated by crossing over 30$% of the time) then that means they are 30 map units apart
Sex linked traits - located on sex chromosomes
Determine biological sex in animals
Non homologous
X and Y letter designations
They deviate from mendel mode of inheritance
Some traits result from non-nuclear inheritance
Chloroplast and mitochondria contain non-nuclear genomes
Chloroplast and mitochondria are randomly assorted into gametes and daughter cells during cell division bc they are just in the cytoplasm
Mitochondria are transmitted to the egg, not the sperm in animals !!
Mitochondrial traits are maternally inherited
Traits determined by chloroplast and mitochondrial DNA do not follow medallion rules
Can be determined through pedigree
If female is affected by trait, all her children will be too
Environmental effects on phenotype
The same genotype can result in multiple phenotypes
Environmental factors influence gene expression
Phenotypic plasticity is the ability of one genotype to produce more than one phenotype
Example - flower color based on soil pH
In hydrangeas - color of flower is based on pH of soil
Chromosomal inheritance
Law of segregation explains separation of alleles during gamete formation
Each gamete has one allele for each gene
Provides opportunity for more varied alleles
independent assortment - suggests that genes for two or more traits sorted into gametes independently
Assortment of genes independently provides more possible gene combinations
Random fertilization - concept that any genetically unique sperm and egg can combine
Mutated alleles can be inherited (genetic disorders)
Chromosomes can carry mutated alleles
Law of segregation/independent assortment explain how mutations alleles can be distributed into gametes
Genetic disorder if mutation negatively effects
Nondisjunction - failure of chromosomes to fully separate in the formation of gametes
Too many or too few chromosomes
Example - triple x syndrome (3 x chromosomes)
Triploidy is having three copies of a particular chromosome which results in sterility in some animals
polyploidy is having multiple sets of homologous chromosome which is seen mostly in plants
UNIT 6 - Gene Expression and Regulation
DNA is the primary genetic material
Genetic information is stored in sequence of bases
Genetic info is transmitted from one generation to the next
DNA is packaged into chromosomes before its passed to daughter cells
Viruses use RNA
DNA and RNA are structurally similar
Both polymers containing nucleotides
Chain like molecules
Base pairing rules
DNA - adenine and thiamine
Guanine and cytosine
RNA - adenine and uracil
Guanine and cytosine
Specific base pairing is conserved through evolution
DNA and RNA both follow base pairing rules
Pyrimidines pair only with purines
Pyrimidines - single ring structure
Uracil, cytosine, thiamine
Purines - double ring structure
Adenine and guanine
Prokaryotic and eukaryotic genomes differ
Prokaryotic organisms have circular chromosomes while eukaryotes have multiple linear chromosomes
Prokaryotic genomes are smaller than eukaryotic genomes
Prokaryotes and eukaryotes can contain plasmids (small extrachromosomal double-stranded circular DNA molecules)
Prokaryotic plasmids are in cytosol in eukaryotes they are found in the nucleus
Replication
Purpose of replication - ensure continuity of heredity information
Genetic information copied before cell division
Transmission of genetic information from one generation to another
Semiconservative replication - in a DNA molecule, one is the original stand and one is a newly synthesized element
Each original strand is the template for the complementary strand
Directionality influences replication process
Each DNA has phosphate group on one end and hydroxyl group on the other end
5’ and 3’ end
two strands of DNA run antiparallel to each other
Nucleotides can only be added in the 5 to 3 Direction
Strand always synthesized continuously - leading strand
Strand always synthesis discontinuous in fragments - lagging strand
Enzymes involved with DNA replication
helicase unwinds the DNA strands
Topoisomerase relaxes the super coil at the replication fork
replication fork is where the two strands are separated
DNA polymerase synthesizes new strands
it requires RNA primers to initiate synthesis
it attaches to the 3 end of the template
builds strands in a 5 to 3 Direction
Ligase joins DNA fragments on the lagging strand
it connects them together
Genetic information flows from DNA to RNA to protein
Ribosomes contain rRNA that assemble proteins
Transcription- the process in which an enzyme directs the formation of an mRNA molecule
DNA strands separate during transcription
one strand is the template strand also known as The non-coding Strand
the other strand is the non-template Strand also known as the coding strand
The Strand serving as the template depends on the gene being transcribed
the gene targeted for transcription is on the coding strand
The enzyme RNA polymerase synthesizes mRNA in the 5 to 3 Direction by reading the template in a three to five Direction
Three types of RNA
mRNA - carries genetic info from DNA to the ribosomes
Information is used to direct protein synthesis at the ribosomal site
A codon is a three base sequence on mRNA
TRNA - recruited to the ribosomes to help create specific polypeptide sequins directed by MRNA
various tRNA molecules each carrying a specific Amino
the anticodon is a three-based sequence on TR
correct base pairing of TRNA anticodons with mRNA codons release in the addition of an amino acid to a growing polypeptide
rRNA (ribosomal RNA) - molecules are functional units of ribosomes responsible for protein assembly
base pairing of anticodons and codons occur in the ribosome
Transcription and RNA processing
In eukaryotes- a series of enzyme regulated modifications occur to the MRNA transcript
Addition of a poly a tail
100 to 200 adenine nucleotides
addition of a GTP cap
modified guanine nucleotide
helps ribosomes attach to mRNA
Introns - sequences of mRNA that do not code for amino acids
Removed during RNA processing
Not included in mature mRNA
Exons - sequences of mRNA that do code for amino acids
they are retained during RNA processing
they are connected together in the mature mRNA
Splicing introns and connecting retained exons = alternative splicing
Many different exons on a primary transcript
Different mRNA transcripts from one primary transcripts
Exons can be retained in different variations
Different mRNA transcripts lead to different proteins
Translation of mRNA generates polypeptide
Translation occurs on ribosomes
Prokaryote v eukaryote
Prokaryotes only have cytoplasm ribosomes
eukaryotic cells can have cytoplasm or ribosomes bound to the rough endoplasmic reticulum
Three main steps
Initiation
Elongation
Termination
Retrovirus translation is a special case because of alternate flow of information
retroviruses introduced viral RNA instead of DNA into host cells
reverse transcriptase is an enzyme that copies the viral RNA into viral DNA (reverse process to transcription)
reverse transcriptase is a viral enzyme
once the enzyme converts viral RNA into viral DNA the DNA is integrated into the host gen
once integrated the viral DNA will be transcribed and translated
transcription and translation of viral DNA results in assembly of a new viral progeny
Translation - final process in flow of info from DNA to RNA to protein
Converting RNA to protein
Initiation - first step
rRNA interacts with mRNA at first start codon
mRNA codon chart - helps Determine which codon codes for each amino acid
some amino acids are coded for by more than one codon
AUG is the start codon - methionine
Stop codons - UAA, UAG, UGA
Elongation - second step
Each newly arrived tRNA brings another amino acid to a growing peptide chain
rRNA adds the amino acid as tRNA brings it
Termination - last step
Amino acids will continue to be added until a stop codon is reached
the newly synthesized polypeptide is just released
Regulation of gene expression
Differences in the expression of genes account for phenotypic differences between organisms
Gene expression - process where instructions and the DNA are transcribed and translated into a functional protein
Different chemical reactions regulate gene expression
Regulatory sequences or stretches of DNA that can be used to promote or inhibit proteins synthesis
Regulatory proteins - assist promotion or inhibition of protein synthesis
Epigenetic changes involve reversible modifications of DNA or histones
histones are protein that DNA wraps around
slight chemical modifications of DNA and histones cause tight or loose packing of DNA
Observable cell differentiation results from the expression of genes for tissue specific protein
Cells within multicellular organisms all have same DNA sequences
Tissues are groups of cells with the same function
Presence of specific proteins in tissues gives tissues specific functions
Phenotype of a cell is determined by combination of genes expressed
Cell differential - Cells are in the same organism that had different phenotypes
Induction of transcription factors during Development results in sequential gen
transcription factors are proteins that promote or inhibit transcription of gene
Presence of transcription factors helps determine how a cell will differentiate
Both eukaryotes and prokaryotes have genes that are coordinately regulated
Operons are closely linked genes that produce a single mRNA molecule during transcription
They are under control of the same regulatory sequence
Includes genes to be transcribed, regulatory sequence, and operator
Operator is a sequence that either it's or promotes transcription by binding with the regulatory protein
In prokaryotes groups of genes called operons are transcribed in a single mRNA
structural proteins with related functions are typically encoded together in the genome
controlled by a single regulatory sequence
regulatory genes can control the expression of all the genes at the same time
The lac operon is an example of an inducible operon
it's inducible because it's usually turned off
When the regulatory protein is bound to the operator RNA polymerase cannot bind to the regulatory sequence
Inducers are molecules that can bind to the regulatory protein and cause it to change shape
It causes the regulatory protein to release from the operator and frees up on a polymerase to transcribe the operon
Example - other transcription factors that regulate the lac operon
The amount of glucose in the cell helps regulate Gene Expression
when glucose is low other transcription factors bind to the regulatory sequence which can promote transcription
when glucose levels are high these transcription factors are not present
Gene expression and cell specialization
Princess in the expression of genes account for phenotypic differences between organisms
Promoters - DNA sequences that are Upstream of the transcription start site where RNA polymerase and transcription factors bind to initiate transcription
The interaction between regulatory proteins, Regulatory genes, and transcription factors initiates transcription
RNA polymerase is able to transcribe genes in the presence of transcription factors
Negative regulatory molecules can inhibit gene expression by blocking transcription
RNA polymerase is blocked from binding to the promoter
Mutations
Changes in genotype can result in changes in phenotype
mutations are the changes in the genome
Mutations can be positive negative or neutral based on the effect or lack of effect they have on the protein
Substitutions - when one nucleotide is substituted for another
Neutral if the change encodes the intended protein
positive if the change benefits the cell or organism
negative if the change harms the cell organism
insertions/deletions
Shifts the rest of the codons/amino acids
The processing of genetic information is imperfect which leads to genetic variation
disruptions in genes cause new phenotypes
Random mutations caused by:
Errors in DNA replication
Error in DNA repair
Radiation
Reactive chemicals
Mutations are the primary source of genetic variation
Horizontal acquisition of genetic information and prokaryotes increases variation
Transformation- refers to the uptake of naked DNA
naked DNA is DNA not protected by proteins and it comes from an external environmental source
Transfiction - transmission of foreign DNA into a cell when a viral genome integrates with the host genome (think of the bacteriophage (i think))
Conjugation - cell to cell transfer of DNA
Allows small segments of DNA to move from one cell to another
Transposition - movement of DNA segments within DNA molecules (cross sign over)
Biotechnology
Genetic engineering tehnoques Can be use to analyze and manipulate DNA and RNA
Electrophoresis
Separates molecules based on size and charge
DNA molecule are negativity charged
Put DNA on negaitve side bc moves towards positive
It separated DNA fragents by size
Smaller will move further through gel
polymerase chain reaction(PCR)
DNA fragments are amplified
Allow scientists to create large samples of DNA when only small samples are available
Steps
DNA is denatured (seperating helix)
Primers are added
DNA is replicated
Keeps doubling DNA
DNA sequencing
Determines order of nucleotides in DNA molecule
Nucleotides being labeled with dye to read DNA
UNIT 7 - Natural Selection
Intro to evolution + natural selection:
Natural Selection: any population of organisms, there's variation
Process where environmental factors will select certain variations
Some variations don't matter but some do a lot
Example: bacteria culture
Every 1 in a billion are different
Bc of factors like mutations/random changes
Antibiotic that kills the majority, but doesnt kill the 1 in a billion, so that continues to grow and the bacteria/virus will keep growing
Biodiversity + Natural Selection
Evolution: 2 pathways - Pattern + Process
Pattern: shape of evolution
Relationships of organisms overtime
Phylogenetic tree
Diff organisms/events that link organisms together
Process: drivers of diversity
Ex: all 4 legged animals have similarity but some differences about other aspects
Natural Selection: fitting the circumstances of the environment + surviving
Fitness: better able to produce offspring that had beneficial traits of the parent - Survival of the fittest
Adaptations: traits that make better to survive/reproduce
Adapt to an environment that can change.
Hardy Weinberg Equilibrium
Allele Frequency
Allele: gene variant
Frequency of allele = (number of copies of allele X in population)/(total number of copies of gene in population)
Example: B = brown eyes b = blue eyes - 2 people starts with: one Bb and one bb
Frequency of B (f(B)) = ¼ (25%)
Frequency of b (f(b)) = ¾ (75%)
Diff than phenotype % which would be 50% brown eyes and 50% blue eyes
p is frequency of dominant allele and q is frequency of recessive allele
p+q = 1
Hardy Weinberg Equation
Hardy weinberg principle assumptions - stable allele frequencies
No natural selection that would change allele frequency (no more fit allele)
No mutations
Large populations
p + q = 1 (bc two alleles) (they both equal 100%)
Square both sides : (p+q)2 = 12
p2 + 2pq + q2 = 1
p2 = p*p (frequency of dominant allele)2
Probability of getting TWO dominant alleles
Probability of someone being homozygous dominant
q2 = q*q (frequency of recessive allele)2
Probability of getting TWO recessive alleles
Probability of being homozygous recessive
2pq = pq + qp
Probability of getting heterozygous
Applying the hardy weinberg equation
Example: B=brown b=blue
9% has blue eyes
Can we figure out p and q?
Evidence for Evolution
Evidence for evolution
Structural
Homologous structures: things that have similar position/structure but maybe not the same function
Ex: forearm: humans don't use it, dogs walk on it, birds use it to fly and whales use it to propel in water
All the orgs had a common ancestor
Fossil records: fossils from millions of years ago relate/change into current day organisms
Microbiology/genetics
translating/replicating of dna is very similar between all life
Dna coding for proteins that have amino acids
Humans are very similar to chimpanzees, then mice, then fruit flies then yeast, then a plant
This helps determining how far common ancestors are
Direct observation
Bacteria: using antibiotics, there are some bacteria that are immune, those are the most fit, and the ones that reproduce
Phylogeny
Taxonomy and the tree of life
Taxonomy (carl linnaeus) - classification of organisms
Group species into groups - genus (more specific), class, family, order, class, kingdom(more broad)
Example: humans are homos, so were neanderthals (thats a genus)
Homos and chimpanzees are in the same TRIBE as each other called the homoinus
Homoinus are in the same FAMILY (called the hominidae) as the hominae which includes the gorilla
Understanding and building a phylogenetic tree
Just remember that worksheet
Speciation
Species - animals that can interbreed and the offspring are fertile
Example: lion x lion = lion
Lion x tiger = liger
Liger not fertile so lion and tiger are different species
Could be animals that act the exact same but look different
Dogs are all the same species but can look different
Ex. different dog breeds can mix
Speciation
Allopatric speciation - Formation of new species through geographic separation
Ex. squirrels and the grand canyon
They were the same species but as time went on and the canyon was created, they couldn't mate with each other so their genes changed
Sympatric speciation - behavioral divergence
Ex. american maggot fly has two options to mate on - hawthorne and and apple
Some of them choose the hawthorne and some choose the apple and though the same geographical location, they diverge into two different species because of behavior
Reproductive isolation
Asexual reproduction: one cell reproduces and creates cells that are the exact same as the parent cell
Low genetic diversity
Sexual reproduction: 2 organisms reproduce and create completely different offspring
High genetic diversity
Species divided by reproductive isolation
Prezygotic isolation - different forces that prevent two organisms from having offspring together BEFORE creation of zygote
temporal/habitat isolation - two organisms mate at different times/places
Behavioral isolation - attract by singing song etc
Mechanical isolation - mating is not possible bc of size
Elephant x mouse wouldn't work
Gametic isolation - It's impossible for two gametes to produce a zygote bc of chromosome number
Postzygotic isolation
Zygor mortality - create zygote but has high mortality rate
Hybrid inviability - zygote creates offspring but offspring has high mortality rate
Hybrid sterility - zygote grows into adult but is infertile
UNIT 8 - Ecology
Organisms respond to changes in their environment through behavior and physiological mechanisms
a stimulus is an external or internal signal that causes a response from an organism
Organism exchange information with one another in response to internal and external signal
Signaling behavior
Produces changes in other organisms
Leads to differential reproudctuve success
Communication mechanisms
Visual, audible, tactile, electrical, chemical
Uses
Dominance, find food, establish territory, ensure reproductive success
Response and communication impact natural selection and evolution
Natural selection favors behaviors that increase survival and reproructive success
Innate Behaviors are controlled and can occur without prior experience or training
learn behaviors are developed as a result of experience
Cooperative behaviors involve teamwork between organisms of the same species
Increases Fitness of individual and survival of population
Example: warning traits
Discourage predation
Aposematism
Markings, behaviors, chemicals
Ex. coral snakes have red and yellow back banding that indicates they are venomous
Energy flow through ecosystems
Organisms use different strategies to regulate body temperature and metabolism
endotherms use thermal energy generated by metabolism to maintain homeostatic body temperatures
Ex. change in heart rate/fat storage
Ectotherms lack efficient internal mechanisms to regulate and maintain body temperatures
rely on behaviors to regulate temperature example moving into or out of the Sun
There is a relationship between metabolic rate per unit of body mass and the size of the organism
Metabolic rate is the amount of energy expended by an animal over a specific amount of time
Net gain in energy = energy storage/growth
Net loss of energy = loss of math or death
smaller the organism the higher the metabolic rate
Different organisms use various reproductive strategies in response to energy availability
some species produce a lot of Offspring at one time
less energy efficient
more common in unstable environments where resources are not available
some species produce very few Offspring at one time
More energy efficient
more common in stable ecological environment
Changes in energy availability can result in changes in population size ( disruption to ecosystem )
a change in energy resources such as sunlight can affect the number and size of the trophic levels
a change in the producer level can affect the number and size of other trophic levels
A trophic level is a position an organism occupies in a food chain
Food chain - shows direction of nutrient and energy transfer from one organism to another
Each organism occupies a different trophic level and reflects how many energy transfers separated from the producer
example: primary producer to primary consumer to secondary consumer to tertiary consumer to Apex consumer to decomposer
Food webs consist of many interconnected food chains
the transfer of energy between trophic levels is inefficient around 10% efficiency
the Energy Efficiency limits the length of food chains and the size of population
population size decreases as trophic level goes up
The activities of autotrophs and heterotrophs enable the flow of energy within an ecosystem
autotrophs are organisms that capture energy from physical or chemical sources in an environment
photo autotrophs capture energy presence sunlight
chemoautotrophs capture energy from small inorganic molecules in their environment without oxygen
heterotrophs capture energy present in physical carbon compounds produced by other organisms
they metabolize carbohydrates, lipids, proteins as a source of energy by hydrolysis
Different organisms use various reproductive strategies in response to energy availability
plants produce pollen at times of the year when pollinators will be active
animals reproduce in the spring and summer when food is available for offspring
reproduction is triggered by a critical photo period - photo. being the relative length of day and night
example: grizzly bears mate between May and July
females delay implantation of eggs in the uterus until November or December
Poulatiion ecology
A population is comprised of individual organisms of the same species
individuals interact with one another in complex way
individuals within a population usually interbreed with one another rather than individuals from another population
Adaptations are related to obtaining and using energy in a particular environment
the size of populations depends on availability of resources
when food is less available the population decreases
reproduction rates decrease in Offspring survivability decrees
different species have adaptations that Aid in survival when energy availability changes
example: storage of fat during winter, losing leaves or growing leaves, migrating
Factors that can affect population growth
age at reproductive matur
number offsprijg produced
frequency of reproduction
survivors of Offspring ability to reproductive maturity
population growth formula
DN = change in population
DT = change in time
b = birth rate
D = death rate
Reproduction without constraints results in exponential growth of population
exponential growth refers to a sharp increase in the growth of a population
occurs under ideal conditions when resources are abundant
exponential growth equation
change in population over change in time equals population size times maximum per capital growth rate of population
Effect of density on populations
Resource availability in an environment impacts population density
population density is how close individuals within a population live near one another
when abundance of food is available the population can become
when food is limited that density may decrease
limits to population growth are due to density dependent and independentfactors
density dependent factors are abiotic or biotic factors whose effect on population size relies on a population density
competition for resources, territory, disease, predators
Density independent factors are factors that affect the population size regardless of population density
floods, Forest fires, pollution
A population can produce a density of individuals that exceeds the system's resource availability
a logistic growth model describes population growth that initially starts slowly immediately followed by exponential growth and ends up with a relatively stable maximum growth
Under certain conditions a population can temporarily exceed the carrying capacity
limiting factors bring the population size back
the population size fluctuates naturally at carrying capacity
Population Dynamics can be represented using mathematical models
logistic growth equation
Community ecology
the structure of a community is described according to the composition and diversity of species
community is a group of different species living together in the same location and interacting with one another
communities are described based on species diversity and species composition
species diversity is the variety of species and quantity of individuals in each species
species composition refers to the identity of each species
Simpsons diversity index
Is used to measure the biodiversity of a habitat
the higher the index value the more diverse it is
based on random samples of the environment
Interactions among populations determine how they Access Energy and matter
communities change over time depending on interactions between populations
competition is an interaction that can affect how populations Access Energy and matter
competition over food or habitats
it can be positive negative or neutral
positive interactions
mutualism where both species benefit
commensalism where one species benefits and the other is neutral
negative interactions
predator and pray where one species is a food source
parasitism where one species benefits at the harm of another
neutral interactions
just simply two organisms living in the same environment not competing for anything
Relationships among interacting populations can be characterized by positive and negative effects and models
Predator prey interactions
and increase in Predator population occurs after an increase in pray population
and increase in the Predator population will eventually cause a decrease in prey population
a trophic Cascade refers to the negative effect the removal of or decrease in a key species has on other trophic levels
Niche partitioning refers to the decrease in competition over limited resources between two similar species
Biodiversity
Ecosystem diversity is related to its resilience to changes in the environment
natural and artificial ecosystems with fewer component parts and with little diversity are less resilient to changes in the environment
the diversity of species within an ecosystem May influence the long-term structure of an ecosystem
less vulnerable to drastic structural changes when organisms are added or removed
Abiotic factor (nonliving factors (wind/rain)) and biotic factors (living organisms in environment
abiotic factors can help maintain ecosystem diversity
climate, nutrient availability, light availability
biotic factors help maintain ecosystems diversity
producers maintain ecosystem diversity
many populations depend on producers for food and habitat
dominant Predators keep prey populations under control
diverse diets
The effects of keystone species are disproportionate relative to their abundance
keystone species are species the community structure depends on
when they are removed from the ecosystem the ecosystem collapses
example predators that control the size of populations so when that keystone species is gone overpopulation depletes resources
Disruptions to ecosystems
evolution is characterized by the change in genetic makeup of a population over time
adaptation is a genetic variation of a trait that is favored by selection
Invasive species affect ecosystem Dynamics
invasive species- is one that is not native to the specific area and harm the community it is introduced to
the introduction of an invasive species can be intentional or unintentional
invasive species exploit new niche
Out compete other organisms for resources
The disruption of local and Global ecosystems changes over time
habitat change can occur because of human activity
human impact accelerates change at local and Global levels
urbanization deforestation erosion Extinction pollution climate change disease
Geological and meteorological activities can change ecosystems
Examples: large habitat disruptions, chemical disruptions, reproductive isolation
