Choose the correct statements from the following related to glycine amino acid.
(A). Water soluble α-amino acid.
(B). It has both amino and carboxylic groups in its structure.
(C). It is optically inactive.
(D). It is a non-essential amino acid.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B), (C) and (D)
Glycine, \( \ce{H2N-CH2-COOH} \), is the simplest amino acid: its side chain R is only a hydrogen atom. Like other amino acids it has an amino group and a carboxyl group on the same (α) carbon, and in water it exists as a dipolar ion (zwitter ion):
\( \displaystyle \ce{H2N-CH2-COOH <=> H3N^+-CH2-COO^-} \)
(A) Water soluble α-amino acid. — Correct. The amino group is on the α-carbon, next to the carboxyl group, and the ionic zwitter ion form makes glycine soluble in water (and gives it a high melting point).
(B) It has both amino and carboxylic groups in its structure. — Correct. \( \ce{-NH2} \) and \( \ce{-COOH} \) are the two groups that every amino acid has; because of them glycine reacts with both acids and bases (amphoteric).
(C) It is optically inactive. — Correct. Its α-carbon carries two hydrogen atoms, so it has no chiral carbon. Glycine is the only naturally occurring α-amino acid that is optically inactive.
(D) It is a non-essential amino acid. — Correct. The body can make glycine, so it need not come from the diet (essential amino acids such as valine and leucine must be taken in food).
NCERT (2026-27 edition):
Classification of Amino Acids – “… Amino acids are usually colourless, crystalline solids. These are water-soluble, high melting solids and behave like salts rather than simple amines or carboxylic acids. This behaviour is due to the presence of both acidic (carboxyl group) and basic (amino group) groups in the same molecule. In aqueous solution, the carboxyl group can lose a proton and amino group can accept a proton, giving rise to a dipolar ion known as zwitter ion.”
Classification of Amino Acids – “… Except glycine, all other naturally occurring α-amino acids are optically active, since the α-carbon atom is asymmetric.”