How does translation termination differ between prokaryotes and eukaryotes?

• A. Prokaryotes terminate using a single release factor; eukaryotes use multiple release factors.
• B. Termination signals are identical in prokaryotes and eukaryotes.
• C. Prokaryotes use RF1/RF2 (and RF3) to recognize stop codons; eukaryotes use eRF1 with eRF3; both hydrolyze to release polypeptide.
• D. Only prokaryotes use release factors; eukaryotes do not require them.

Answer: (C)

Termination relies on release factors that recognize stop codons and trigger the cutting of the peptide from the tRNA. In bacteria, there are two specialized factors: RF1 and RF2. Each recognizes different stop codons (RF1 for UAA and UAG, RF2 for UAA and UGA), ensuring that all three stop signals are correctly identified. A third factor, RF3, is a GTPase that helps recycle and speed up the process by promoting the release factors’ departure from the ribosome after hydrolysis. In eukaryotes, termination uses a single factor, eRF1, which recognizes all three stop codons, working with eRF3 to promote termination. In both systems, the actual release of the polypeptide comes from hydrolysis of the bond between the polypeptide and the tRNA. That combination of distinct stop-codon recognition in bacteria versus a universal stop-codon recognition by a single factor in eukaryotes, along with the shared hydrolytic release step, is what this option accurately describes.