The two functional groups found in all amino acids are:

• The amino group (–NH₂), which consists of a nitrogen atom bonded to two hydrogen atoms.
• The carboxyl group (–COOH), which consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (OH).

These groups are attached to a central (alpha) carbon atom along with a hydrogen atom and a variable side chain (R group) unique to each amino acid