ap biology final vocab terms

ionic

a bond formed by the transfer of electrons, creating oppositely charged ions that attract each other

covalent

A bond formed when atoms share one or more pairs of electrons.

carbon

An element with four valence electrons that forms the backbone of organic molecules.

energy

The capacity to do work or cause change.

phosphate

A functional group consisting of a phosphorus atom bonded to four oxygen atoms; important in energy transfer (ATP).

electronegativity

The ability of an atom to attract electrons toward itself.

partial charges

Slight positive or negative charges on atoms in a polar covalent bond due to unequal electron sharing.

valence shell

The outermost electron shell of an atom that determines its bonding behavior.

anion

A negatively charged ion.

cation

A positively charged ion.

Dipole moment

A separation of charge in a molecule resulting from unequal electron sharing.

endergonic

A reaction that requires an input of energy (ΔG > 0).

Exergonic

A reaction that releases energy (ΔG < 0).

Reactant

A starting substance in a chemical reaction.

Product

A substance produced by a chemical reaction.

Equilibrium

A state where forward and reverse reactions occur at equal rates.

Homeostasis

The maintenance of stable internal conditions despite external changes.

pH (hydrogen ions and hydroxyls)

A measure of acidity based on the concentration of H⁺ and OH⁻ ions.

Law of conservation of energy

Energy cannot be created or destroyed, only transformed.

Law of conservation of matter

Matter cannot be created or destroyed in chemical reactions.

Anabolic

Metabolic pathways that build complex molecules from simpler ones.

Catabolic

Metabolic pathways that break down complex molecules into simpler ones.

Molarity

The concentration of a solution measured as moles of solute per liter of solution.

Biological macromolecules

Large organic molecules including carbohydrates, proteins, lipids, and nucleic acids.

Carbohydrate

Organic molecules composed of carbon, hydrogen, and oxygen

Sugars

Simple carbohydrates (monosaccharides and disaccharides) used for energy.

Starch

A polysaccharide used by plants for energy storage.

Protein

A polymer of amino acids that performs structural, enzymatic, and regulatory functions.

Amino acids

Monomers of proteins consisting of an amino group, carboxyl group, R group, and central carbon.

Terminus

The end of a polypeptide chain (N-terminus or C-terminus).

Primary structure

The linear sequence of amino acids in a protein.

Secondary structure

Local folding of a polypeptide (α-helices and β-sheets) stabilized by hydrogen bonds.

Tertiary structure

The overall 3D shape of a protein formed by R-group interactions.

Quaternary structure

The association of multiple polypeptide chains into one functional protein.

Peptide bonds

Covalent bonds linking amino acids together.

Enzymes

Proteins that act as biological catalysts by lowering activation energy.

Lipid

Hydrophobic molecules including fats, oils, phospholipids, and steroids.

Phospholipids

Amphipathic lipids that form the bilayer of cell membranes.

Nucleic acid

Polymers that store and transmit genetic information (DNA and RNA).

Nucleotides

Monomers of nucleic acids composed of a sugar, phosphate group, and nitrogenous base.

Pyrimidine

A single-ring nitrogenous base (C, T, U).

Purine

A double-ring nitrogenous base (A, G)

RNA

A single-stranded nucleic acid involved in protein synthesis.

DNA

A double-stranded nucleic acid that stores genetic information.

ATP

Adenosine triphosphate; the primary energy currency of the cell.

Polymerization

The process of forming polymers from monomers.

Polymer

A large molecule composed of repeating monomer units.

Monomer

A small molecular unit that can be linked to form a polymer.

Hydrolysis

A reaction that breaks bonds using water.

Dehydration synthesis / condensation

A reaction that forms bonds by removing water.

Water

A polar molecule essential for life due to its hydrogen-bonding ability.

Polar

A molecule with unequal charge distribution.

Nonpolar

A molecule with equal charge distribution.

Hydrogen bonds

Weak attractions between a partially positive hydrogen and a partially negative atom.

Hydrophobic

Water-repelling; nonpolar.

Hydrophilic

Water-attracting; polar or charged.

Charged

Having a net positive or negative electrical charge.

Uncharged

Having no net electrical charge.

Water potential

A measure of the tendency of water to move based on solute concentration and pressure.

Aquaporins

Membrane proteins that facilitate water transport.

Turgor pressure

Pressure exerted by water against a plant cell wall.

Tonicity

The ability of a solution to cause water movement across a membrane.

Plasmolysis

The shrinking of a plant cell’s cytoplasm due to water loss in a hypertonic solution.