Question

The α amino acid which contains an aromatic side chain is:
A.Proline
B.Tyrosine
C.Valine
D.Serine

Answer 1

Hint:Aromatic ring refers to the presence of an aromatic compound. The proteins are molecules which consist of an ammoniated group and an acid present. The loss of water from the ammoniated group and acid forms a peptide bond. The amino acids exist in zwitter ionic form in which both have a different charge on the same molecule.

Complete step by step answer:
Aromatic amino acids consist of an aromatic ring. There are 3 of the aromatic amino acids among the 20 present; these are phenylaniline, tyrosine and tryptophan. All the amino acids are essential amino acids. Essential amino acids are those which are not produced by our body and we need to add it from outside via dietary supplements. Deficiency of essential amino acids causes different kinds of illness. The deficiency of phenylaniline is generally due to the lack of phenylaniline hydrolysis which causes phenylketonuria. Tyrosine deficiency causes stunted growth and tryptophan deficiency causes Blue diaper syndrome. The structure of tyrosine is 4-hydroxyphenylalanine and hence in an aniline group there is a phenyl ring present which is aromatic in nature. Tyrosine is obtained from high protein food like chicken, fish, peanuts etcHence the answer is option B tyrosine.

structure of tyrosine.

Note:
 Proline is an essential amino acid but is not aromatic. It contains a pyrrolidine ring and an acid group present. The body conditions convert it into a carboxylate ion and are thereby basic. It is used to generate different types of proteins. It is a straight chain amino acid which contains an isopropyl group hence we find that it is not aromatic. Serine is a non essential amino acid. It is the precursor of many proteins. It is an aliphatic aromatic compound. Thus they are not the correct option.