Question

Which of the following feature is true about ALL twenty genetically coded amino acids?

• A. They are optically active
• B. They contain a methylene group in their side chain
• C. They contain Carbon, Hydrogen, Oxygen, and Nitrogen
• D. They are basic in nature

Hint:

Amino = Nitrogen; Acid (Carboxyl) = Carbon, Oxygen, Hydrogen. CHON is the rule.

Answer 1

The Correct Option is C

Step 1: Concept
Amino acids are the building blocks of proteins, sharing a common fundamental structure.

Step 2: Analysis
All amino acids have an amino group ($-NH_2$), a carboxyl group ($-COOH$), and a hydrogen atom attached to a central carbon (the $\alpha$-carbon).

Step 3: Elimination
- (A) is false because Glycine is not optically active (it lacks a chiral center). - (B) is false because some side chains (like Glycine) do not have a methylene group. - (D) is false because some are acidic, polar, or non-polar.

Step 4: Conclusion
Every amino acid, regardless of its side chain, must contain Carbon, Hydrogen, Oxygen, and Nitrogen. Final Answer: (C)