AP Bio Fall Final Review

evolution

changes in populations, species, or groups of species; the process by which the frequency of heritable traits in a population changes from one generation to the next

natural selection

“survival of the fittest”

paleontology

provides fossils that reveal the prehistoric existence of extinct species , resulting in studies in changes in species and the formation of new species

biogeography

uses geography to describe the distribution of species, which has revealed unrelated species in different regions of the world look alike when found in similar environments

embryology

reveals similar stages in development (ontogeny) among related species, and the similarities help establish evolutionary relationship (phylogeny)

homologous structures (homologies)

body parts that resemble one another in different species because they have evolved from a common ancestor

vestigal

when homologous structures no longer serve any function

analogous structures (analogies)

body parts that resemble one another in different species, not because they have evolved from a common ancestor, but because they evolved independently as adaptations to their environment

molecular biology

examines the nucleotide and amino acid sequence of DNA and proteins from different species

adaptations

an inherited trait (physical, physiological, or behavioral) that increases an organism's chances of survival and reproduction in its specific environment, becoming more common in a population through natural selection over generations

fitness

relative ability to survive and leave offspring

darwin’s theory for evolution by natural selection

1. populations possess an enormous reproductive potential

2. population sizes remain stable

3. resources are limited

4. individuals compete for survival

5. variation among individuals in a population

6. much variation is heritable

7. only the most fit individuals survive

8. evolution occurs as favorable traits accumulate in the populations

stabilizing selection

favoring of intermediate trait

directional selection

favoring of one extreme phenotype

disruptive selection

favors extreme phenotypes and selects against common ones

sexual selection

favoring of favorable traits for mating

sexual dimorphism

differences in the appearance of males and females

artificial selection

form of directional selection carried out by humans when they breed animals that possess desirable traits

mutations

change in the genetic material of an organism that provide the raw material for new variation

sexual reproduction

creates individuals with new combinations of alleles that originate from:

1. crossing over: exchange of DNA between nonsister chromatids of homologous chromosomes

2. independent assortment of homologues: creates daughter cells with random combinations of maternal and paternal chromosomes

3. random joining of gametes: contributes to the diversity of gene combinations in the zygote during fertilization

diploidy

presence of two copies of each chromosomes in a cell

outbreeding (mating with unrelated partners)

increases the possibility of mixing different alleles and creating new allele combinations

balanced polymorphism

maintenance of different phenotypes in a population

heterozygote advantage

occurs when the heterozygous condition bears a greater selective advantage than either homozygous condition

hybrid vigor (heterosis)

describes the superior quality of offspring resulting from crosses between two different inbred strains of plants

frequency-dependent selection (minority advantage)

occurs when the least common phenotypes have a selective advantage

gene flow

the movement of individuals between populations resulting in the removal of alleles from a population when they leave or the introduction of alleles when they enter

genetic drift

random increase or decrease of alleles

founder effect

a type of genetic drift that occurs when allele frequencies in a group of migrating individuals are, by chance, not the same as that of their population of origin, and the new population will only resemble the individual found in the smaller population

bottleneck effect

a type of genetic drift that occurs when a population undergoes a dramatic decrease in size and can leave a random assortment of survivors

nonrandom mating

occurs when individuals choose mates based upon their particular traits

hardy weinberg equiliibrium

at genetic equilibrium, there is no evolution; however, the following conditions must be true:

1. all traits are selectively neutral (or natural selection

2. mutations don’t occur

3. the population must be isolated from other populations (no gene flow)

4. population is large (no genetic drift)

5. mating is random

allopatric speciation

begins when a population is divided by a geographic barrier so that interbreeding between the two resulting populations is prevented

sympatric speciation

formation of new species without the presence of a geographic barrier that can happen due to:

1. balanced polymorphism

2. polyploidy: the possession of more than the normal set of chromosomes found in diploid cells

3. hybridization: occurs when two distinctly different forms of a species (or closely related species that are normally reproductively isolated) mate and produce progeny along a geographic boundary called a hybrid zone

adaptive radiation

relatively rapid evolution of many species from a single ancestor

prezygotic isolating mechanisms

mechanisms that prevent fertilization:

1. habitat isolation: species don’t encounter one another

2. temporal isolation: species mate during different seasons or at different times of day

3. behavioral isolation: species does not recognize another species as a mating partner because it doesn’t perform the correct courtship rituals, display the proper visual signs, sing the correct mating songs, or release the proper chemicals

4. mechanical isolation: male and female genitalia are structurally incompatible

5. gametic isolation: male gametes don’t survive in the environment of the female gamete of when female gametes don’t recognize male gametes

postzygotic isolating mechanisms

consists of mechanisms that prevent the formation of fertile progeny:

1. hybrid inviability: when the zygote fails to develop properly and aborts or dies before reaching reproductive maturity

2. hybrid sterility: hybrids become functional adults, but are reproductively sterile

3. hybrid breakdown: hybrids produce offspring that have reduced viability or fertility

divergent evolution

two or more species that originate from a common ancestor and become increasingly different over time that can happen as a result of allopatric or sympatric speciation or adaptive radiation

convergent evolution

two unrelated species that share similar traits that arise because each species has independently adapted to similar ecological conditions or lifestyles

parallel evolution

two related species or two related lineages that have made similar evolutionary changes after their divergence from a common ancestor

coevolution

the reciprocal evolutionary change where two or more species influence each other's adaptations through close interactions

microevolution

the details of how populations of organisms change from generation to generation

macroevolution

general patterns of change in groups of related species that have occurred over broad periods of geologic time

punctuated equilibrium

evolutionary history consists of geologically long periods of stasis with little or no evolution, interrupted by geologically short periods of rapid evolution

ionic bond

form between 2 atoms when one or more electrons are transferred from one atom to the other; the atom that gains electrons has an overall negative charge, and the atom that loses electrons has an overall positive charge, meaning these atoms are ions

covalent bonds

form when electrons between atoms are shared, meaning that neither atom completely retains possession of the electrons

nonpolar covalent bonds

form when electrons are shared equally

polar covalent bonds

form when electrons are shared unequally

hydrogen bonds

weak bonds between molecules that form when a positively charged hydrogen atom in one covalently bonded molecule is attracted to a negatively charged area of another covalently bonded molecule

solvent

the substance (usually a liquid, like water) that dissolves another substance

hydrophilic

“water loving”

hydrophobic

“water fearing”

solute

substance that dissolves in a solvent

aqueous

a solution in which water is the solvent

specific heat capacity

the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius

heat of fusion

energy required to change water from a solid to a liquid

heat of vaporization

energy required to change water from liquid to a gas

cohesion

attraction between like substances that occurs in water cause of the hydrogen bonding between water molecules

surface tension

strong cohesion between water molecules produces a high surface tension, creating a water surface that is firm and allows it to resist an external force, behaving like a stretched elastic membrane

adhesion

attraction of unlike substances resulting from the attraction of the poles of water molecules to other polar substances

capillary action

the upward movement of a liquid (like water) through narrow spaces (capillaries in plants, tubes) against gravity, driven by the combined forces of adhesion (water sticking to tube walls) and cohesion (water molecules sticking to each other), along with surface tension, crucial for plant water transport from roots to leaves

monosaccharide

simplest kind of carbohydrate that consists of a single sugar molecule

disaccharide

2 sugar molecules joined by a glycosidic linkage

dehydration synthesis

a chemical reaction that joins two molecules together by removing a water molecule, forming a new covalent bond and creating a larger molecule called a polymer. In this process, the hydroxyl group of one monomer combines with a hydrogen atom from another, releasing a water molecule and linking the monomers

polysaccharide

a series of connected monosaccharides, making it a polymer

saturated fatty acid

a long hydrocarbon chain with only single bonds between its carbon atoms, meaning it's "saturated" with the maximum number of hydrogen atoms, giving it a straight, rigid shape that packs tightly, making fats solid at room temperature

unsaturated fatty acid

a lipid with one or more carbon-carbon double bonds in its hydrocarbon tail, causing kinks that prevent tight packing, keeping them liquid at room temperature (like oils) and crucial for membrane fluidity, especially in varying temperatures

phospholipid

an amphipathic lipid (hydrophilic "head" + hydrophobic "tails") that forms the cell membrane's bilayer, consisting of a phosphate group, glycerol, and two fatty acids, creating a selectively permeable barrier for the cell

transport proteins

specialized membrane proteins that move ions, small molecules, or larger substances across the cell membrane

peptide bonds

bonds between amino acids

primary structure

describes the order of amino acids

secondary structure

3D shape that results from hydrogen bonding between the amino and carboxyl groups of nearby amino acids, producing a spiral (alpha helix) or a folded plane that is pleated (beta pleated sheet)

tertiary structure

includes addition 3D shaping with the following contributing to the structure:

1. hydrogen bonding between R groups of amino acids

2. ionic bonding between R groups of amino acids

3. hydrophobic effect that occurs when hydrophobic R groups move to the center of the protein (away from water)

4. formation of disulfide bonds that help maintain the folds of the amino acid chain

quaternary structure

a protein that is assembled from 2 or more separate peptide chains

DNA nucleotide

• consists of a nitrogen base, five-carbon sugar (deoxyribose), and a phosphate group

• DNA nucleotides

  • adenine (purine)

  • thymine (pyrimidine)

  • cytosine (pyrimidine)

  • guanine (purine)

RNA vs. DNA

1. sugar in the nucleotides that make an RNA molecule is ribose, not deoxyribose as it is in DNA

2. the thymine nucleotide doesn’t occur in RNA and is replaced by uracil that pairs with adenine

3. RNA is usually single-stranded and doesn’t form a double helix as it does with DNA

activation energy

the minimal energy needed to kickstart a chemical reaction

enzymes

• proteins that act as catalysts for metabolic reactions

• characteristics:

  • enzymes are substrate specific

  • an enzyme is unchanged as a result of a reaction an can perform its enzymatic function repeatedly

  • an enzyme catalyzes a reaction in both forward and reverse directions

  • the efficiency of an enzyme is affected by temperature and pH; if they are not optimal, the enzyme will denature

  • the induced fit model describes how enzymes work

induced fit model

explains enzyme-substrate interaction as a dynamic process where the enzyme's active site changes shape slightly upon substrate binding, creating a tighter, more precise fit

substrate

the substance or substances upon which the enzyme acts

hydrolysis

when water and energy from ATP break the last phosphate bond of the ATP molecule to form ADP and an inorganic phosphate group

phosphorylation

new ATP molecules are assembled by phosphorylation when ADP combines with a phosphate group using energy obtained from energy-rich molecules

allosteric activator

a molecule that binds to an enzyme at a site other than the active site (an allosteric site) to change the enzyme's shape, which increases its activity and affinity for its substrate, speeding up the reaction

allosteric site

a specific region on an enzyme where a regulatory molecule binds, causing a change in the enzyme's activity.

allosteric inhibitor

a molecule that binds to an enzyme at a site other than the active site (an allosteric site), causing a conformational (shape) change that reduces the enzyme's activity, often by preventing the substrate from binding effectively to the active site, thereby regulating metabolic pathways through negative feedback. 

feedback inhibition

the end product of a metabolic pathway inhibits an earlier enzyme in the same pathway, slowing down or stopping its own production

competitive inhibition

a substance that mimics the substrate inhibits an enzyme by occupying the active site, preventing the enzyme from catalyzing the substrate

noncompetitive inhibition

a substance inhibits the action of an enzyme by binding to the enzyme at a location other than the active site and changes the shape of the enzyme, disabling enzyme activity

selectively permeable membrane

only small, uncharged, polar molecules and hydrophobic molecules freely pass across the membrane

channel proteins

provide open passageways through the membrane for certain hydrophilic substances such as polar and charged molecules

aquaporins

channel proteins that increase the passage rate of water molecules

ion channels

allow the passage of ions across the membrane

carrier proteins

bind to specific molecules, which are then transferred across the membrane after the carrier protein undergoes a change in shape

transport protein

uses energy to transport materials across the membrane; type of active transport

recognition proteins

give each cell type a unique identification, providing a distinction between cell types

receptor proteins

provide binding sites for hormones or other trigger molecules, causing a specific cell response to be activated

cholesterol

distributed throughout the phospholipid bilayer to provide some stability to the plasma membranes of animal cells; at high temperature, it helps maintain firmness, and at cool temperatures, it keeps the membrane flexible

ribosomes

synthesize proteins by translating messenger RNA (mRNA) into polypeptide chains

rough er

when ribosomes are present, it creates glycoproteins and its primary role is the synthesis, folding, modification, and transport of proteins destined for secretion, insertion into membranes, or delivery to other organelles

smooth er

responsible for synthesis of lipids and steroid hormones and breaking down toxins, drugs, and toxic by products in the liver