Final answer:
The initiator tRNA does not bring methionine during the termination step of translation; its function is in the initiation phase. Termination includes reaching a stop codon, releasing the polypeptide, and the ribosomal subunits separating.
Step-by-step explanation:
The termination step of translation involves several key events once a stop codon is reached on the mRNA. This includes the release of the polypeptide chain, release factors binding to the stop codon, and the dissociation of the ribosomal subunits. However, during the termination step, the initiator tRNA does not bring methionine, as its role is confined to the initiation step of translation. Additionally, release factors bind to the stop codon. However, the initiator tRNA bringing the amino acid methionine does not occur during translation's termination step.
During translation, the process begins with the initiator tRNA carrying methionine to match the start codon on the mRNA. As translation progresses through the elongation phase, amino acids are added to the growing polypeptide chain. Once a stop codon (UAA, UAG, or UGA) is encountered, translation termination is triggered. Release factors bind to the stop codon, prompting the polypeptide to be released from the ribosome. The ribosomal subunits then separate and dissociate from the mRNA to be recycled for future translation processes. It is during this final phase of translation that the initiator tRNA adding methionine does not occur, as its function is strictly linked to the commencement of the translation process.