Final answer:
Translation termination occurs when a stop codon is encountered during protein synthesis. Stop codons signal the end of translation, leading to the release of the polypeptide chain and the dissociation of ribosome subunits.
Step-by-step explanation:
Translation termination occurs when a stop codon (UAA, UAG, or UGA) is encountered during protein synthesis. The stop codon serves as a termination signal, indicating that the ribosome should stop translating the mRNA. At this point, the growing polypeptide chain is released, and the ribosome subunits dissociate from the mRNA. After translation is complete, the mRNA is degraded.
Stop codons do not code for an amino acid, and their function is to signal the end of protein synthesis. They instruct the ribosome to stop adding amino acids to the polypeptide chain. The reading frame for translation is set by the start codon (AUG) near the 5' end of the mRNA.
In summary, stop codons are important elements in the genetic code that mark the end of protein synthesis. They halt translation, leading to the release of the polypeptide chain and the dissociation of ribosome subunits.