Question

A protein is a sequence of amino acids. The end of polypeptide chain of -NH2 end and -COOH end are respectively called ............

• A. α-terminal and β-terminal
• B. N-terminal and C-terminal
• C. C-terminal and N-terminal
• D. β-terminal and α-terminal

Hint:

The N-terminal refers to the end of the polypeptide chain with an amino group, and the C-terminal refers to the end with a carboxyl group.

Answer 1

The Correct Option is B

Step 1: Understanding the structure of a protein.
The N-terminal is the beginning of the polypeptide chain where the amino group (-NH2) is located, and the C-terminal is the end of the chain where the carboxyl group (-COOH) is located.
Step 2: Analyzing the options.
(A) α-terminal and β-terminal: Incorrect. These are not standard terms used for the ends of a polypeptide chain.
(B) N-terminal and C-terminal: Correct. The amino acid sequence has an N-terminal (amino group) and C-terminal (carboxyl group).
(C) C-terminal and N-terminal: Incorrect. This is reversed.
(D) β-terminal and α-terminal: Incorrect. These terms are not used in the context of polypeptide chain ends.
Step 3: Conclusion.
The correct answer is (B) N-terminal and C-terminal, as these terms correctly describe the ends of a polypeptide chain.