Basic Chemistry and Biochemistry: Key Concepts and Definitions

atom

Smallest particle of an element

ion

A charged atom

element

A pure substance made of only one kind of atom

isotope

Atoms of the same element that have different numbers of neutrons

molecule

A group of atoms bonded together

compound

A substance made up of atoms of two or more different elements joined by chemical bonds

organic molecule

A molecule containing carbon that is a part of or produced by living systems.

functional group

A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions.

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

ionic bond

Formed when one or more electrons are transferred from one atom to another

hydrogen bond

weak attraction between a hydrogen atom and another atom

amino acid

Building blocks of protein

peptide bond

The chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid

protein primary structure

sequence of amino acids

protein secondary structure

The folding of the primary structure of a protein. This folding is caused principally by hydrogen bonds. The result is beta-sheets, alpha-helices, and random coils.

protein tertiary structure

Three-dimensional shape formed by interactions between R groups.

carbohydrate

compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body

mono-, di-, polysaccharide

a carbohydrate whose molecules consist of a number of sugar molecules bonded together

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

nucleic acid

macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

lipid

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.

triglyceride

a lipid made of three fatty acid molecules and one glycerol molecule

sterol

a type of lipid with a structure composed of multiple chemical rings

phospholipid

a lipid that contains phosphorus and that is a structural component in cell membranes

electrolyte

An ionic compound whose aqueous solution conducts an electric current

polar molecule

molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end

O

oxygen

N

nitrogen

C

carbon

Ca

calcium

P

phosphorus

K

potassium

S

sulfur

Na

sodium

Cl

chlorine

Mg

magnesium

Fe

iron

I

iodine

H2O

water

CO2

carbon dioxide