Chemistry of Life (AP Biology)

Vocabulary-style flashcards covering key terms from the Chemistry of Life lecture notes.

Structure leads to function

The idea that the arrangement of atoms in monomers and polymers determines their biological function.

Monomer

A small molecule that can join with others to form polymers.

Polymer

A large molecule composed of repeating monomer units linked by covalent bonds.

Dehydration synthesis

A chemical reaction that links monomers by removing a water molecule.

Hydrolysis

A reaction that breaks polymers into monomers by adding water.

Covalent bond

A strong bond formed by sharing electrons between atoms; energy is required to form and break.

Ionic bond

An electrostatic attraction between oppositely charged ions; dissociates easily in water.

Polar covalent bond

A covalent bond with unequal sharing of electrons, creating partial charges.

Nonpolar covalent bond

A covalent bond with equal sharing of electrons; no significant partial charges.

Electronegativity

An atom's tendency to attract electrons in a bond.

Hydrogen bond

A weak attraction between a δ+ hydrogen and a δ− atom in another molecule.

Hydration shell

A shell of water molecules around ions or polar molecules in solution.

Solvent

The dissolving medium in a solution.

Solute

The substance dissolved in a solvent.

Cohesion

Water molecules sticking to other water molecules.

Adhesion

Water molecules sticking to other substances.

Capillary action

Movement of water through narrow tubes due to adhesion to surfaces and cohesion within.

Glycosidic bond

Bond linking monosaccharides in carbohydrates; formed by dehydration synthesis.

Monosaccharide

Simple sugar; building block of carbohydrates (e.g., glucose).

Disaccharide

Two monosaccharides joined by a glycosidic bond.

Polysaccharide

Complex carbohydrate; long chains of monosaccharides; energy storage or structure.

Glucose

A common hexose sugar; primary energy source for cells.

Starch

Plant storage polysaccharide made of glucose; consists of amylose and amylopectin.

Glycogen

Animal storage polysaccharide; highly branched glucose polymer.

Cellulose

Structural polysaccharide in plant cell walls; beta-linkages; not digestible by humans.

Chitin

Structural polysaccharide in arthropod exoskeletons and fungal cell walls.

Lipid

Hydrophobic biomolecule, primarily composed of carbon and hydrogen; includes fats, oils, steroids; energy storage and membranes.

Triglyceride

Lipid with three fatty acids attached to glycerol; main energy storage form.

Fatty acid

Long hydrocarbon chain with a carboxyl group; tails of lipids.

Saturated fatty acid

Fatty acid with only single bonds; typically solid at room temperature.

Unsaturated fatty acid

Fatty acid containing one or more double bonds; chain kink; typically liquid at room temperature.

Steroid

Lipid with four fused carbon rings; includes hormones and cholesterol.

Cholesterol

Steroid molecule that helps stabilize membranes and is a precursor to steroids.

Phospholipid

Lipid with two fatty acids and a phosphate-containing head; forms the lipid bilayer of membranes.

Membrane bilayer

Double layer of phospholipids forming cell membranes; hydrophobic core.

Nucleic acids

DNA and RNA; polymers made of nucleotides; store and express genetic information.

Nucleotide

Monomer of nucleic acids; consists of a sugar, a phosphate, and a nitrogenous base.

Deoxyribose

Five‑carbon sugar in DNA (lacks one oxygen compared to ribose).

Ribose

Five‑carbon sugar in RNA; has a hydroxyl group on the 2' carbon.

Purine

Two-ring nitrogenous bases (adenine and guanine).

Pyrimidine

One-ring bases (cytosine, thymine, uracil).

Adenine

Purine base; pairs with thymine in DNA and with uracil in RNA.

Thymine

Pyrimidine base; pairs with adenine in DNA.

Cytosine

Pyrimidine base; pairs with guanine.

Guanine

Purine base; pairs with cytosine.

Uracil

Pyrimidine base; replaces thymine in RNA and pairs with adenine.

Base pairing

A pairs with T (DNA) or with U (RNA); G pairs with C.

Antiparallel

DNA strands run in opposite 5' to 3' directions.

5' to 3' direction

Directionality of nucleic acid synthesis; nucleotides added at the 3' end.

DNA

Double-stranded, deoxyribose-containing nucleic acid; stores genetic information.

RNA

Single-stranded nucleic acid; ribose sugar; involved in protein synthesis; uses uracil.

Amino acid

Monomer of proteins; central carbon bonded to an amino group, a carboxyl group, hydrogen, and an R group.

Peptide bond

Bond between the amino group of one amino acid and the carboxyl group of the next.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Hydrogen bonds in the backbone cause alpha-helices or beta-pleated sheets.

Tertiary structure

Three-dimensional folding due to R-group interactions (hydrogen bonds, ionic, hydrophobic, disulfide bridges).

Disulfide bridge

Covalent bond between cysteine residues stabilizing the tertiary structure.

Quaternary structure

Interactions between multiple polypeptides to form a functional protein.

Denaturation

Loss of a protein's structure and function due to heat, pH, salts, or detergents.

Enzyme

Biological catalyst; speeds up reactions by lowering activation energy; substrate-specific.

Active site

Region of an enzyme where the substrate binds; may change shape upon binding.

Substrate

Reactant that binds to an enzyme's active site.

Enzyme-substrate complex

Temporary complex formed during catalysis.

Optimal temperature

Temperature at which enzyme activity is maximal.

pH

A measure of acidity; low pH = high H+; high pH = low H+.

Activator

Molecule that increases enzyme activity; may be a coenzyme.

Inhibitor

Molecule that decreases enzyme activity; includes competitive and noncompetitive types.

Cofactor

Inorganic helper molecule (e.g., metal ions) needed by some enzymes.

Coenzyme

Organic helper molecule required by some enzymes.

Competitive inhibition

Inhibitor binds to the active site, blocking substrate access.

Noncompetitive (allosteric) inhibition

Inhibitor binds elsewhere on the enzyme, changing the active site's shape.

Feedback inhibition

Product inhibits an earlier enzyme in a pathway to regulate production.

Endorphin

Natural opioid peptide that binds endorphin receptors; morphine mimics it.

Morphine

Opioid drug that binds to endorphin receptors.

Endorphin receptor

Receptor in the brain that binds endorphins to mediate effects.