Solution:

Glycine is the amino acid that has a single hydrogen atom as its side chain. It is the simplest possible amino acid. The chemical formula of glycine is NH2-CH2-COOH. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG.

Leucine is an essential branched-chain amino acid important for haemoglobin formation. Leucine is one of nine essential amino acids in humans (provided by food), Leucine is important for protein synthesis and many metabolic functions.

Isoleucine is an essential branched-chain aliphatic amino acid found in many proteins. It is an isomer of LEUCINE.

Histidine is an alpha-amino acid with an imidazole functional group. It is one of the 22 proteinogenic amino acids. Histidine was first isolated by German physician Albrecht Kossel in 1896. Histidine is an essential amino acid in humans and other mammals.