What is the name of the amino acid whose structure is given below?

The correct answer is Option (2) → Alanine

An α-amino acid has the general formula \( \ce{R-CH(NH2)-COOH} \); the amino acids differ only in the side chain R. In the given structure the α-carbon carries –COOH, –NH₂, H and a methyl group:

    \( \displaystyle \ce{CH3-CH(NH2)-COOH} \)

So R = –CH₃, the side chain of alanine.

Why the other options are incorrect

Option (1) Glycine — Incorrect. Its side chain is H; it has no methyl group: \( \ce{H2N-CH2-COOH} \).

Option (3) Proline — Incorrect. Its nitrogen is part of a ring (–NH– joined back to the side chain); the given structure is open-chain with a free –NH₂.

Option (4) Threonine — Incorrect. Its side chain is \( \ce{H3C-CHOH-} \), which carries an extra –OH group.

NCERT (2026-27 edition):
Table 10.2: Natural Amino Acids