What happens during translation termination?

• A. Stop codon is recognized by release factors, promoting hydrolysis of the polypeptide from the tRNA and ribosome dissociation.
• B. Stop codon causes tRNA to detach.
• C. Ribosome re-initiates translation at nearby start codon.
• D. mRNA is degraded before translation ends.

Answer: (A)

During translation termination, a stop codon in the mRNA sits in the ribosome’s A site and is recognized by release factors rather than a tRNA. These release factors catalyze the hydrolysis of the bond between the growing polypeptide and the tRNA in the P site, releasing the completed protein. After release, the ribosome disassembles from the mRNA, aided by recycling factors, so translation can begin anew if needed.

The other ideas don’t fit this step: a stop codon doesn’t trigger detachment of tRNA itself, termination isn’t about the ribosome re-initiating at a nearby start codon, and mRNA degradation is not an obligatory part of the termination event.