What happens at a STOP codon during translation?

What happens at a STOP codon during translation?

• A. It signals initiation of translation
• B. Protein synthesis stops and the polypeptide is released
• C. It replaces a start codon
• D. It is ignored by the ribosome

Answer: (B)

During translation, a STOP codon signals the end of protein synthesis. It isn’t read by a tRNA because stop codons don’t code for amino acids. Instead, release factors recognize the stop codon at the ribosome and trigger the release of the newly made polypeptide by hydrolyzing the bond between the polypeptide and the tRNA. After release, the ribosome dissociates from the mRNA and translation is complete. Initiation is guided by a start codon, not a stop codon, and there’s no tRNA that matches a stop signal, so stopping is the correct outcome.

During translation, a STOP codon signals the end of protein synthesis. It isn’t read by a tRNA because stop codons don’t code for amino acids. Instead, release factors recognize the stop codon at the ribosome and trigger the release of the newly made polypeptide by hydrolyzing the bond between the polypeptide and the tRNA. After release, the ribosome dissociates from the mRNA and translation is complete. Initiation is guided by a start codon, not a stop codon, and there’s no tRNA that matches a stop signal, so stopping is the correct outcome.