Question

Amino acid that is not hydrophilic is

• A. Histidine
• B. Phenylalanine
• C. Glycine
• D. Lysine

Answer 1

Answer: (B)

Phenylalanine

In a peptide chain, amino acids are joined together by peptide bonds. Amino acids are amphoteric compounds having both basic (amino) group as well as acidic (carboxylic) group. Hence, the name amino acids. Amino acids are organic compounds made up of carbon, hydrogen, oxygen, nitrogen and sulphur. The amino, carboxylic and substituent groups are attached to the $\alpha$-carbon atom which also binds a hydrogen atom. In some amino acids the substituent group contains hydrophobic aromatic ring, e.g., phenylalanine, tyrosine and tryptophan. In glycine the substituent group is an atom of hydrogen. In histidine the substituent group is heterocyclic and in lysine it is basic. i.e., diamino monocarboxylic group.

So, the correct answer is option B.