Which phase lengthens the growing polypeptide chain?

• A. Initiation
• B. Elongation cycle
• C. Termination
• D. Translocation

Answer: (B)

The growing polypeptide chain lengthens during the elongation cycle of translation. In this phase, the next aminoacyl-tRNA binds to the A site, a peptide bond forms to attach that amino acid to the existing chain, and the ribosome translocates to move the new chain into position for the next cycle. Each cycle adds one amino acid, so the chain gets longer. Initiation sets up the ribosome and the first amino acid but doesn’t extend the chain beyond the starting point. Termination ends translation and releases the finished protein. Translocation is the moving step that occurs during elongation and helps position the ribosome for the next round, but the actual lengthening happens during the elongation cycle.