Chapter 2

A molecule that releases a proton when dissolved in water; generates hygronium ions, thereby lowering pH.

Small organic molecule containing both an amino group and a carboxyl group; serves as the building block of proteins.

The smallest particle of an element that still retains distinctive chemical properties; consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons.

The mass of an atom expressed in daltons, the atomic mass unit that closely approximates the mass of a hydrogen atom.

Molecule that serves as the principal carrier of energy in cells; composed of adenine, ribose, and three phosphate groups.

Molecule that accepts a proton when dissolved in water; used to refer to the nitrogen-containing purines or pyrimidines in DNA and RNA.

Mixture of weak acids and bases that maintains the pH solution by releasing and taking up protons.

An exchange of electrons that holds two atoms together.

Combination of atoms, or an amino group, with distinct chemical and physical properties that influences the behavior of the molecule in which it resides.

Chemical reaction in which a covalent bond is formed between two molecules as water is expelled; used to build polymers.

Precise, three-dimensional shape of a protein or other macromolecule based on the spatial location of its atoms in relation to one another.

Stable chemical link between two atoms produced by sharing one or more pairs of electrons.

Force that draws together oppositely charged atoms.

Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain.

A weak noncovalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom.

Chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water.

Molecule or part of a molecule that readily forms hydrogen bonds with water, allowing it to dissolve.

Nonpolar, uncharged molecule or part of a molecule that forms few or no hydrogen bonds with water molecules and therefore do not dissolve.

Not composed of carbon and hydrogen

An atom carrying an electrical charge, either positive or negative.

Interaction formed when one atom donates electrons to another, making both atoms become electrically charged.

Organic molecule that is insoluble in water but dissolves in nonpolar organic solvents.

Thin pair of closely juxtaposed sheet, composed mainly of phospholipid molecules, that forms the structural basis for all cell membranes.

Polymer built from covalently linked subunits; includes proteins, nucleic acids, and polysaccharides with a molecular mass greater than a few thousand daltons.