Final answer:
Termination is the stage of translation when a ribosome reaches a stop codon, leading to the release of the new polypeptide and the dissociation of the ribosomal subunits for reuse.
Step-by-step explanation:
The stage of translation that occurs when a ribosome reaches a stop codon is called termination. This process takes place when the ribosome encounters any of the three stop codons (UAA, UAG, or UGA) in the mRNA sequence. During termination, a release factor recognizes the stop codon, prompting the ribosome to stall. This allows the newly synthesized polypeptide chain to be released. The ribosomal subunits then dissociate from the mRNA and from each other, and they can be reused in another round of translation. The mRNA that has been translated is eventually degraded, allowing its nucleotides to be recycled for future transcription reactions.