Polypeptide synthesis
A)proceeds from the C-terminus to the N-terminus.
B)proceeds from the N-terminus to the C-terminus.
C)proceeds in both directions simultaneously.
D)proceeds in either direction once initiated.
E)proceeds randomly.

Question

Quizplus · Accepted Answer

Polypeptide synthesis always proceeds from the N-terminus (amino end) to the C-terminus (carboxyl end) of a protein. This is because the amino acids that make up the protein are added to the growing peptide chain via peptide bonds between the amino group (-NH2) of one amino acid and the carboxyl group (-COOH) of another amino acid. As each new amino acid is added to the chain, the carboxyl group at the end of the chain becomes unavailable for further reaction. Therefore, the N-terminus remains available for new amino acids to be added, while the C-terminus is at the end of the chain.

Polypeptide Synthesis