Match List-I (amino acid) with List-II (Characteristic Side Chain)
|
List-I Amino acid |
List-II Characteristic Side Chain |
|
(A) Phenylalanine |
(I) \( (CH_3)_2CHCH_2- \) |
|
(B) Leucine |
(II) \( C_6H_5CH_2- \) |
|
(C) Lysine |
(III) \( CH_3-CH_2-CH(CH_3)- \) |
|
(D) Isoleucine |
(IV) \( H_2N-(CH_2)_4- \) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
All α-amino acids have the general formula \( \ce{R-CH(NH2)-COOH} \); they differ only in the side chain R, which gives each its name and character (non-polar, aromatic, basic, acidic).
(A) Phenylalanine — This matches (II) \(C_6H_5CH_2-\). The side chain is a benzyl group, which makes it an aromatic amino acid.
(B) Leucine — This matches (I) \((CH_3)_2CHCH_2-\). The side chain is an isobutyl group, branched at the second carbon from the α-carbon.
(C) Lysine — This matches (IV) \(H_2N-(CH_2)_4-\). The side chain carries a second amino group at the end of four \( \ce{CH2} \) groups, which makes lysine a basic amino acid.
(D) Isoleucine — This matches (III) \(CH_3-CH_2-CH(CH_3)-\). The side chain is a sec-butyl group, branched at the first carbon; leucine and isoleucine are isomers that differ only in the place of the branch.
Shortcut: (A)-(II) with (B)-(I) appears in Options (1) and (2); (C)-(IV) then leaves only Option (1).
NCERT (2026-27 edition):
Amino Acids – …
