What part of an amino acid changes to create different amino acids?
Each amino acid has a unique R group as explained below.
All amino acids contain a central carbon atom which is bonded to an amino group, a hydrogen atom, a carboxylic acid group, and an R group. The R group varies with each amino acid.
The simplest R group is a hydrogen atom, which forms the amino acid glycine.
The following is a list of the 20 amino acids that occur in nature. Note that each one has a different R group.