Question

True statements about collagen: A. Triple-stranded helical structure
B. Repeating tripeptide Gly-X-Y
C. ‘a chains' are right-handed helix
D. Glycine permits sharp twisting
E. Ascorbic acid is required for proline hydroxylation

• A. A, B, C, D and E
  (2) A, B, C and D only
  (3) A, B, D and E only
  (4) A, B and E only
• B.
• C.
• D.

Hint:

Remember: Individual alpha-chain = Left-handed. Triple helix (together) = Right-handed.

Answer 1

The Correct Option is C

Step 1: Concept
Collagen is the main structural protein in connective tissues with a specific “triple helix” structure. Step 2--3: Analysis
A is correct: It is a triple helix.
B is correct: It follows a Gly-X-Y repeating pattern.
C is incorrect: Individual alpha chains are left-handed helices; they form a right-handed super-helix together.
D is correct: Glycine (the smallest amino acid) fits in the tight centre.
E is correct: Vitamin C (Ascorbic acid) is the cofactor for proline hydroxylation.

Step 4: Conclusion
Statements A, B, D, and E are true.

Final Answer: (3)