Question

1. what is the r - group of an amino acid?

Explanation:

An amino - acid has a central carbon atom bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and an R - group. The R - group is the variable part that gives each amino - acid its unique properties. It can be a simple hydrogen atom (in glycine), an alkyl group, an aromatic group, or a group with functional groups like hydroxyl, sulfhydryl, etc.

Answer:

The variable side - chain of an amino - acid that gives it unique chemical properties.