AP Biology Comprehensive Study Guide Flashcards

A collection of vocabulary flashcards based on the AP Biology study guide, covering biochemistry, cell biology, energetics, genetics, evolution, and ecology.

Polar compounds

Molecules like water that have distinct regions of charge based on bond structure.

Hydrogen bonds

Weak bonds that form between a proton in one molecule and an electronegative atom of another molecule, such as the bond between the oxygen of one water molecule and the hydrogen of another.

Cohesion

The tendency of molecules of the same kind to stick together, which in water creates surface tension.

Surface tension

The tendency of liquid surfaces to shrink to minimize surface area, allowing solid matter to float at the surface.

Adhesion

The tendency of dissimilar molecules to be attracted to each other, such as water being attracted to charged surfaces.

Capillary action

The movement of liquid through spaces on its own, sometimes in opposition to gravity, caused by adhesive forces between water and a surface.

Polymers

Structures made of repeating smaller units called monomers, including carbohydrates, proteins, and nucleic acids.

Dehydration synthesis

A reaction where a covalent bond forms between two monomers, releasing a water molecule and using energy that is then stored in the bond.

Hydrolysis

The process of breaking down polymers into monomers by lysing the covalent bond using water, which releases energy for the cell to use.

Primary structure

The composition and specific order of amino acids in a polypeptide chain.

Secondary structure

Protein folds arising from interactions between elements in the amino acid backbone, including $\alpha$ helixes and $\beta$ sheets.

Tertiary structure

The 3D shape of a protein resulting from interactions between R groups, which minimizes free energy to achieve the most stable position.

Quaternary structure

The complex structure formed by interactions between amino acids on different polypeptide chains.

Glycosidic bond

The covalent bond formed between a carbohydrate and another molecule through dehydration synthesis.

Saturated fatty acid

A lipid chain where all neighboring bonds in the hydrocarbon chain are single bonds, allowing them to pack tightly and remain solid at room temperature.

Unsaturated fatty acid

A lipid chain containing double bonds that cause a bend (cis) in the chain, preventing tight packing and resulting in liquid oils at room temperature.

Phosphodiester bond

The covalent bond in a DNA or RNA polymer that connects the phosphate group to two sugar groups.

Prokaryotes

Unicellular organisms, such as bacteria and archaea, that do not have cell walls, membrane-bound organelles, or a nucleus, and typically possess a single circular chromosome.

Eukaryotes

Organisms with multiple chromosomes organized in a membrane-bound nucleus and other specialized organelles, including plants, animals, and fungi.

Mitochondria

Membrane-bound organelles where cellular respiration and the synthesis of ATP from ADP occur; they possess their own circular DNA and double membranes.

Chloroplasts

Membrane-bound organelles containing chlorophyll that perform photosynthesis; like mitochondria, they have their own DNA and protein synthesis machinery.

Ribosomes

Structures made of ribosomal RNA ($rRNA$) and proteins that perform translation of RNA into protein; they can be free in the cytoplasm or bound to the rough ER.

Golgi apparatus

A series of membrane sacks where protein modification occurs and where proteins are packaged and targeted for export from the cell.

Lysosomes

Vesicles containing hydrolytic enzymes used to destroy proteins, cell waste, and damaged organelles.

Fluid mosaic model

A model describing the plasma membrane as a flexible phospholipid bilayer with embedded cholesterol, proteins, glycolipids, and glycoproteins.

Passive transport

The movement of molecules across a membrane without the use of energy, occurring from areas of high concentration to low concentration.

Active transport

The movement of molecules across a membrane requiring metabolic energy ($ATP$) to move substances against their concentration gradient.

Osmosis

The process by which water moves across a semipermeable membrane from an area of low solute concentration to high solute concentration.

Endocytosis

The process where a vesicle forms in the plasma membrane to take in molecules from the external environment into the cell.

Endosymbiosis

The theory that membrane-bound organelles like mitochondria and chloroplasts evolved from free-living prokaryotes that were engulfed by a eukaryotic cell.

Activation energy

The energy barrier or hurdle that must be overcome for an energy-releasing chemical reaction to occur.

Competitive inhibitors

Molecules that compete for an enzyme's active site, preventing the substrate from binding and blocking the reaction.

Noncompetitive inhibitors

Molecules that bind to a site other than the active site, changing the enzyme's conformation so it can no longer bind the substrate effectively.

Bioenergetics

The study of energy transformation in living organisms.

Metabolism

The general term for all energy transformations in living organisms, including anabolism and catabolism.

Anabolism

The process where molecules store energy in the form of chemical bonds.

Catabolism

The process by which energy is released by breaking chemical bonds within molecules.

Photolysis

The light-dependent reaction of photosynthesis that takes place in the thylakoid membranes, generating $ATP$ and $NADPH$ while releasing oxygen.

Calvin cycle

The light-independent reaction of photosynthesis occurring in the stroma, where $CO_2$ is fixed into small 3-carbon sugars using $ATP$ and $NADPH$.

Glycolysis

The first step of cellular respiration in the cytosol, where a 6-carbon glucose is broken down into two 3-carbon pyruvates, two $ATP$, and two $NADH$.

Chemiosmosis

The process by which a proton gradient is used by the enzyme ATP synthase to convert $ADP$ to $ATP$.

Fermentation

A process that regenerates $NAD^+$ from $NADH$ in the absence of oxygen, converting pyruvate into lactic acid or alcohol to allow glycolysis to continue.

Ligand

A signaling molecule released into the extracellular space to be received by a cell with a specific receptor.

Paracrine signaling

A form of communication where a cell releases a ligand to signal to nearby cells, such as neurotransmitters at a synapse.

Endocrine signaling

Long-distance signaling where a cell releases ligands, such as hormones, into the bloodstream to affect distant cells.

Homeostasis

The relatively constant state of the internal environment maintained by negative feedback mechanisms.

Interphase

The stage of the cell cycle where cells grow and copy their DNA, consisting of the $G_1$, $S$, and $G_2$ phases.

Mitosis

The process of cell division resulting in two daughter cells with identical DNA, consisting of prophase, prometaphase, metaphase, anaphase, and telophase.

Apoptosis

The process of regulated or programmed cell death.

Meiosis

A two-round form of cell division that creates four non-identical haploid gametes from a diploid cell.

Crossing over

The exchange of DNA between homologous pairs of chromosomes during prophase I of meiosis, also known as recombination.

Law of Segregation

Mendel's law stating that allele pairs separate when gametes are formed, meaning each gamete receives only one copy of each gene.

Genotype

The specific variants of a gene (alleles) that an individual organism possesses.

Phenotype

The physical expression or observable trait of an organism's genotype.

Semiconservative replication

The mechanism of DNA replication where one original strand serves as a template for the synthesis of a new complementary strand.

Helicase

The enzyme responsible for separating double-stranded DNA into single strands to allow access for replication machinery.

Topoisomerase

An enzyme that works ahead of the replication fork to prevent DNA supercoiling by breaking and resealing the phosphate backbone.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during replication.

Transcription

The process where RNA polymerase makes a complementary $mRNA$ copy of a DNA gene sequence.

Alternative splicing

A posttranslational modification in eukaryotes where exons are selectively included or excluded, allowing one gene to code for multiple protein sequences.

Reverse transcriptase

An enzyme used by retroviruses to transcribe single-stranded viral $RNA$ into double-stranded DNA.

Operon

A group of genes in prokaryotes that are regulated and transcribed together as a single unit with one promoter.

Genetic drift

A mechanism of evolution involving random fluctuations in the frequency of a trait within a population, typically seen in small, isolated groups.

Allopatric speciation

The formation of new species occurring when populations are geographically isolated by a physical barrier.

Adaptive radiation

The rapid evolution of many diverse types from a single ancestor to fill vacant ecological niches, often following mass extinctions.

Oparin-Haldane Hypothesis

The theory that life arose through gradual chemical evolution in an oxygen-poor, reducing atmosphere on early Earth.

Miller-Urey Experiment

A landmark experiment that demonstrated that organic building blocks of life, like amino acids, could form from inorganic precursors in conditions mimicking early Earth.

RNA world hypothesis

The proposal that $RNA$ was the first self-replicating information storage molecule on Earth due to its ability to store information and act as a catalyst (ribozyme).

Carrying capacity

The maximum population size ($K$) that a specific environment can sustainably support based on available resources.

Trophic cascades

Occur when a predator suppresses the abundance or alters the behavior of their prey, thereby releasing the next lower trophic level from predation.

Keystone species

A species that has a disproportionately large effect on its natural environment relative to its abundance; its removal often leads to ecosystem collapse.

Simpson’s Diversity Index

A mathematical measure of species diversity within a community, calculated as $1 - \Sigma (\frac{n}{N})^2$.