Which component catalyzes peptide bond formation during translation?

• A. tRNA
• B. rRNA
• C. mRNA
• D. DNA polymerase

Answer: (B)

Peptide bond formation during translation is carried out by the ribosome’s RNA component. The ribosome is a complex of RNA and protein, but the chemical step that links amino acids—moving the growing polypeptide from the tRNA in the P site to the aminoacyl-tRNA in the A site—is driven by the large-subunit ribosomal RNA. This rRNA forms the peptidyl transferase center and acts as a ribozyme, stabilizing the transition state and enabling the nucleophilic attack that creates the new peptide bond. The substrates come from the tRNAs and the template from the mRNA, while DNA polymerase handles DNA replication, not translation. So the key catalytic player is the ribosomal RNA.