Question

Which amino acid from following contains —CH$_3$ as side chain?

• A. Leucine
• B. Alanine
• C. Serine
• D. Valine

Hint:

Alanine is the simplest chiral amino acid with a methyl side chain.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Amino acids have a general structure \(\text{H}_2\text{N-CH(R)-COOH}\), where \(R\) is a specific side chain that identifies the amino acid.
Step 2: Key Formula or Approach:
Memorize the basic side chains of the 20 standard amino acids.
Step 3: Detailed Explanation:
1. Leucine: Side chain is isobutyl, \(-\text{CH}_2\text{CH}(\text{CH}_3)_2\).
2. Alanine: Side chain is methyl, \(-\text{CH}_3\).
3. Serine: Side chain is hydroxymethyl, \(-\text{CH}_2\text{OH}\).
4. Valine: Side chain is isopropyl, \(-\text{CH}(\text{CH}_3)_2\).
Step 4: Final Answer:
Alanine is the amino acid with a \(-\text{CH}_3\) side chain.