HORTICULTURE

Detailed explanation-1: -The difference in the side-chain group or R-group is what determines the unique properties of each amino acid.

Detailed explanation-2: -Proline is unique among the standard amino acids in that it does not have both free -amino and free -carboxyl groups. Instead, its side chain forms a cyclic structure as the nitrogen atom of proline is linked to two carbon atoms.

Detailed explanation-3: -Each of the 20 amino acids has a specific side chain, known as an R group, that is also attached to the carbon. The R groups have a variety of shapes, sizes, charges, and reactivities.

Detailed explanation-4: -Amino acid side chain: The portion of alpha-amino acid structure other than the amino group (or the ammonium group in an ionic form), the alpha carbon, and the carboxylic acid group (or the carboxyl group in an ionic form).