During protein synthesis, when does translation stop?

• A. When the tRNA carrying methionine binds to the ribosome
• B. When the ribosome reaches the 5' end of the mRNA
• C. When a stop codon is encountered on the mRNA
• D. When a start codon is encountered on the mRNA

Answer: (C)

Verified step by step guidance

1. Understand that translation is the process where the ribosome reads the mRNA sequence to synthesize a protein by linking amino acids together.
2. Recall that translation begins at a start codon (usually AUG) on the mRNA, which signals the ribosome to start assembling the protein.
3. Recognize that translation continues as the ribosome moves along the mRNA, reading codons and bringing in corresponding tRNAs with amino acids.
4. Identify that translation stops when the ribosome encounters a stop codon on the mRNA. Stop codons do not code for any amino acid and signal the end of protein synthesis.
5. Therefore, the key event that causes translation to stop is the recognition of a stop codon by the ribosome, which triggers the release of the newly made protein.