Are molecules whose general structure includes a central carbon with a carboxyl group, an amine group, a hydrogen molecule, and a residual (r) group.

The amino acids are the molecules where we can found the carboxyl group (-), amino group (-), hydrogen atom (H) and a residual R-group. On the structure of the residual R-group the name of the amino acid depends. Like if R is hydrogen (H) the amino acid is alanine; If R- group is a phenyl group i.e. , the compound is called phenyl alanine. The structure of the general amino acid skeleton can be shown as-