[Campbell Biology P.402] Which of the following is a key difference between the elongation a... | Practice Question
Which of the following is a key difference between the elongation and termination phases of translation, as illustrated in Figures 17.20 and 17.21?
A: In termination, a release factor binds to the A site instead of an aminoacyl tRNA, whereas in elongation, aminoacyl tRNAs always bind to the A site.
B: Elongation requires GTP hydrolysis for each step, while termination does not require any GTP hydrolysis.
C: Termination leads to the formation of a peptide bond, while elongation releases the polypeptide.
D: Stop codons are recognized by specific tRNAs in termination, whereas regular codons are recognized by specific tRNAs in elongation.
Explanation
Figure 17.21, step 1 clearly states that a release factor, shaped like a tRNA, binds to the A site when a stop codon is reached, instead of an aminoacyl tRNA. In contrast, Figure 17.20 shows aminoacyl tRNAs binding to the A site during elongation.