AP BIO VOCAB

homeostasis

the ability of an organism to maintain stable internal conditions despite external environmental changes

metabolism

the sum of all chemical reactions occurring in a cell or organism

enzyme

a protein that speeds up all chemical reactions by lowering activation energy

substrate

the molecule that an enzyme binds to and acts upon

activation energy

minimum amount of energy required to start a chemical reaction

denaturation

the loss of a protein’s structure and function due to extreme temperature, pH, or other environmental changes

competitive inhibition

form of enzyme regulation where a molecule competes with the substrate for the enzyme’s active site

allosteric regulation

regulation of an enzyme by binding a molecule at a site other than the active site, changing the enzyme’s shape and activity

cohesion

attraction between molecules of the same substance

adhesion

attraction between molecules of different substances

monomer

a small molecule that serves as a building block for larger molecules

polymer

a large molecule made of repeating monomers

dehydration synthesis

a reaction that forms a bond between molecules by removing a water molecule

hydrolysis

a reaction that breaks bonds between molecules using water

evolution

the change in the genetic makeup (allele frequencies) of a population over generations

natural selection

the process in which individuals with traits that increase survival and reproduction leave more offspring, causing those traits to become more common in a population

adaptation

a heritable trait that improves an organism’s ability to survive and reproduce in a particular environment

fitness

An organism's reproductive success compared to others in the population.

genetic variation

Differences in DNA sequences among individuals in a population.

gene pool

The total collection of alleles present in a population

allele frequency

The proportion of a specific allele in a population

genetic drift

Random changes in allele frequencies due to chance events

bottleneck effect

A type of genetic drift where a population is drastically reduced in size, decreasing genetic diversity

founder effect

Genetic drift that occurs when a small group establishes a new population

gene flow

The movement of alleles between populations through migration

endosymbiotic theory

The theory that mitochondria and chloroplasts originated as free-living prokaryotic cells that were engulfed by an ancestral eukaryotic cell.

phenotype

The observable physical or biochemical traits of an organism

genotype

The genetic makeup or allele combination of an organism

allopatric speciation

The formation of new species when populations become geographically separated and evolve independently.

sympatric speciation

Speciation that occurs without geographic separation, often due to reproductive isolation within the same area.

reproductive isolation

Mechanisms that prevent different species from mating or producing fertile offspring

punctuated equilibrium

The evolutionary pattern in which species remain relatively unchanged for long periods but experience short bursts of rapid evolution.

gradualism

The idea that evolution occurs slowly and continuously over long periods of time

adaptive radiation

Rapid diversification of a single ancestral species into many different species adapted to different environments

convergent evolution

The evolution of similar traits in unrelated species due to similar environmental pressures

divergent evolution

The process in which related species become increasingly different over time

homologous structures

Structures in different species that share a common ancestry but may have different functions

analogous structures

Structures that have similar functions but evolved independently and do not share a common ancestry

vestigal structures

Anatomical features that have lost most or all of their original function through evolution

hardy-weinberg equilibrium

A principle stating that allele frequencies in a population remain constant if certain conditions (no mutation, migration, selection, small population, or nonrandom mating) are met

sexual selection

A form of natural selection where traits increase mating success rather than survival

artificial selection

The selective breeding of organisms by humans to promote desired traits

secondary messenger

A small intracellular molecule that relays signals from receptors to target molecules inside the cell

phosphorylation cascade

A series of reactions in which proteins activate one another by adding phosphate groups

ligand

A signaling molecule that binds to a receptor protein

receptor protein

A protein that receives chemical signals from outside the cell

autocrine signaling

A type of signaling where a cell targets itself

paracrine signaling

Signaling in which a cell communicates with nearby cells

endocrine signaling

Long-distance signaling where hormones are released into the bloodstream to target distant cells

quorum sensing

A process used by bacteria to detect and respond to the density of their population via signaling molecules.

apoptosis

Programmed cell death triggered by signaling pathways, important in development and tissue maintenance

prokaryote

A cell lacking a nucleus and membrane-bound organelles

eukaryote

A cell containing a nucleus and membrane-bound organelles

binary fission

A form of asexual reproduction in prokaryotes where one cell divides into two identical cells.

mitosis

Cell division that produces two genetically identical daughter cells

meiosis

Cell division that produces four genetically different haploid gametes

diploid

A cell containing two sets of chromosomes (2n)

haploid

A cell containing one set of chromosomes (n)

homologous chromosomes

Chromosome pairs that contain the same genes but may have different alleles

chromatid

One of two identical copies of a replicated chromosome

chromosome

A structure made of DNA and protein that carries genetic information

nondisjunction

Failure of chromosomes to separate properly during cell division, producing cells with abnormal chromosome numbers

gene expression

The process by which information from a gene is used to produce a functional product such as a protein

transcription

The process of synthesizing RNA from a DNA template

translation

The process of synthesizing proteins from mRNA

law of segregation

Mendel's principle that the two alleles for a gene separate during gamete formation

independent assortment

The random separation of chromosome pairs during meiosis

recombination

Exchange of genetic material between homologous chromosomes during meiosis

linked genes

Genes located close together on the same chromosome that tend to be inherited together

operon

A cluster of genes in prokaryotes that are regulated together under a single promoter

promoter

A DNA sequence where RNA polymerase binds to begin transcription

introns

Noncoding segments of a gene removed during RNA processing

exons

Coding segments of a gene that remain in mature mRNA

homozygous

Having two identical alleles for a gene

heterozygous

Having two different alleles for a gene

mutation

A change in the nucleotide sequence of DNA

gene

A segment of DNA that contains the instructions for producing a protein or functional RNA molecule

codon

A three-nucleotide sequence in mRNA that codes for a specific amino acid

polyploidy

A condition where an organism has more than two complete sets of chromosomes

epistasis

When one gene affects or masks the expression of another gene

allele

Different versions of the same gene found at the same locus on homologous chromosomes

locus

The specific physical location of a gene on a chromosome

diffusion

Movement of molecules from high concentration to low concentration

facilitated diffusion

Passive movement of molecules through membrane proteins down their concentration gradient

active transport

Movement of substances across a membrane using energy (ATP) against the concentration gradient

concentration gradient

A difference in the concentration of a substance across a space or membrane

osmosis

Diffusion of water across a selectively permeable membrane

aquaporins

Membrane proteins that facilitate rapid water movement across cell membranes

turgor pressure

Pressure exerted by water inside plant cells against the cell wall

hypotonic solution

A solution with lower solute concentration than the cell, causing water to enter the cell

hypertonic solution

A solution with higher solute concentration than the cell, causing water to leave the cell

isotonic solution

A solution with equal solute concentration as the cell

water potential

The potential energy of water in a system that determines the direction water will move

solute potential

The component of water potential determined by the concentration of dissolved solutes

symbiosis

A close and long-term interaction between two different species

mutualism

A symbiotic relationship where both species benefit

parasitism

A relationship where one organism benefits while the host is harmed

commensalism

A relationship where one organism benefits and the other is unaffected

population

A group of individuals of the same species living in the same area at the same time

community

All the populations of different species living and interacting in the same area