Which term describes the two ends of a polypeptide?

Which term describes the two ends of a polypeptide?

• A. N terminus and C terminus
• B. Alpha terminus and Omega terminus
• C. Beginning end and Ending end
• D. Amino end and Carboxyl end

Answer: (A)

Proteins have two distinct ends defined by their chemistry: one end has a free amino group and is called the N-terminus, while the other end has a free carboxyl group and is called the C-terminus. This naming reflects how polypeptides are built and read—the chain starts at the N-terminus and grows toward the C-terminus. In translation, amino acids are added to the growing chain at the C-terminus, so the direction of synthesis runs from N to C. Other terms like alpha/omega terminus or vague descriptors aren’t standard or precise, whereas N-terminus and C-terminus clearly specify the two ends of a polypeptide.

Proteins have two distinct ends defined by their chemistry: one end has a free amino group and is called the N-terminus, while the other end has a free carboxyl group and is called the C-terminus. This naming reflects how polypeptides are built and read—the chain starts at the N-terminus and grows toward the C-terminus. In translation, amino acids are added to the growing chain at the C-terminus, so the direction of synthesis runs from N to C. Other terms like alpha/omega terminus or vague descriptors aren’t standard or precise, whereas N-terminus and C-terminus clearly specify the two ends of a polypeptide.