Question

1. the 20 amino acids vary only in their

a. carboxyl groups
b. side groups
c. amino groups
d. lipid groups

Explanation:

All 20 amino - acids have a common structure with an amino group, a carboxyl group, and a hydrogen atom attached to the central carbon. The difference between them lies in their side - chains (R - groups). There are no lipid groups in the basic structure of amino acids.

Answer:

B. Side groups