2026 Complete Transcription and Translation Practice Test Prep

Stop codons mark the end of the protein-coding message and signal translation termination. When the ribosome encounters one, release factors bind and trigger the release of the finished polypeptide from the tRNA, effectively stopping translation. They do not encode amino acids, since no amino acid is added at those positions. They are not the start codon—the start codon is AUG and it defines where translation begins. After termination, the ribosome recycling factor helps separate the ribosomal subunits, but the stop codon’s primary role is to signal termination and release the protein, not to recruit recycling factors.