Chemically, an amino acid is a molecule that has a carboxylic acid group and an amine group that are each attached to a carbon atom called the α carbon. Each of the 20 amino acids has a specific side chain, known as an R group, that is also attached to the α carbon.

What are the groups present in amino acids?

Each amino acid contains a central C atom, an amino group (NH2), a carboxyl group (COOH), and a specific R group.

What are the 5 amino acid groups?

There are five main classes of amino acids, those whose R groups are: nonpolar and aliphatic; aromatic (generally nonpolar); polar but uncharged; negatively charged; and positively charged. Within each class there are gradations of polarity, size, and shape of the R groups.