|MoBio||Building Blocks - Amino Acids||Chapter 2|
An amino acid is defined as the molecule containing an amino group (NH2), a carboxyl group (COOH) and an R group. It has the following general formula,
The R group differs among various amino acids. In a protein, the R group is also called a sidechain.
There are over 300 naturally occurring amino acids on earth, but the number of different amino acids in proteins is only 20.