Amino acids contain amino (–NH2) and carboxyl (–COOH) functional groups. Depending upon the relative position of amino group with respect to carboxyl group, the amino acids can be classified as α, β, γ, δ and so on. Only α-amino acids are obtained on hydrolysis of proteins. All α-amino acids have trivial names, which usually reflect the property of that compound or its source. Amino acids are classified as acidic, basic or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Equal number of amino and carboxyl groups makes it neutral; more number of amino than carboxyl groups makes it basic and more carboxyl groups as compared to amino groups makes it acidic. The amino acids, which can be synthesized in the body, are known as nonessential amino acids. On the other hand, those which cannot be synthesized in the body and must be obtained through diet, are known as essential amino acids.
Consider the following statements about the α-amino acids.
(A) Glycine is so named because it has a sweet taste.
(B) Tyrosine is so named because it was first obtained from milk.
(C) Amino acids are generally represented by a three letter symbol, and sometimes a one letter symbol is also used.
(D) Most naturally occurring amino acids have the D-configuration.
Which of the statements given above are correct? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) and (C) only
The α-amino acids have trivial names that usually reflect a property of the compound or its source. They are written as symbols, and in nature nearly all of them have one configuration.
(A) Glycine is so named because it has a sweet taste. — True. The name comes from the Greek glykos, which means sweet.
(B) Tyrosine is so named because it was first obtained from milk. — False. Tyrosine was first obtained from cheese (Greek tyros = cheese), not milk.
(C) Amino acids are generally represented by a three letter symbol, and sometimes a one letter symbol is also used. — True. For example, glycine is Gly or G, and alanine is Ala or A.
(D) Most naturally occurring amino acids have the D-configuration. — False. Most naturally occurring amino acids have the L-configuration, drawn with the –NH2 group on the left hand side.
NCERT (2026-27 edition):
10.2.1 Amino Acids – “Glycine is so named since it has sweet taste (in Greek glykos means sweet) and tyrosine was first obtained from cheese (in Greek, tyros means cheese.) Amino acids are generally represented by a three letter symbol, sometimes one letter symbol is also used.”
10.2.2 Classification of Amino Acids – “…These exist both in ‘D’ and ‘L’ forms. Most naturally occurring amino acids have L-configuration. L-Aminoacids are represented by writing the –NH2 group on left hand side.”