Amino acids are molecules that contain a basic amino group (or NH2-a nitrogen and two hydrogens), an acidic carboxyl group (COOH- a carbon, two oxygen molecules and a hydrogen) and a side chain attached to an alpha carbon atom.
The 20 amino acids are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine.