Question

How many peptide bonds will be there in polypeptide comprising of 10 amino acids?

• A. Ten
• B. Eleven
• C. Twelve
• D. Nine

Hint:

Peptide Bond Rule: In a linear chain of $n$ amino acids, there are $(n-1)$ peptide bonds and $(n-1)$ water molecules released during condensation.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
A linear unbranched polypeptide chain of $n$ amino acid residues contains exactly $n - 1$ covalent peptide bonds.
Key Formula or Approach:
\[ \text{Number of Peptide Bonds} = n - 1 \]

Step 2: Detailed Explanation:
For a linear unbranched peptide:
- Given residue count: \(n = 10\text{ amino acids}\).
- The first amino acid links to the second via 1 bond, the second to third via 1 bond, and so forth.
\[ \text{Total Peptide Bonds} = 10 - 1 = 9 peptide bonds \]
(A cyclic decapeptide would have 10 bonds, but standard polypeptides are linear).

Step 3: Final Answer:
Therefore, there will be Nine peptide bonds, matching option (D).