In elongation, which step is translocation of the ribosome?

In elongation, which step is translocation of the ribosome?

• A. Translocation of ribosomes (tRNA a->P)
• B. Binding of next charged tRNA (A site)
• C. Peptide bond formation (P->A)
• D. Release of free tRNA

Answer: (A)

Translocation is the step in elongation where the ribosome moves along the mRNA by one codon, shifting the tRNAs from the A site to the P site and from the P site to the E site. This movement clears the A site for the next aminoacyl-tRNA to enter and keeps the reading frame aligned with the mRNA. The other steps occur in the cycle at different points: decoding the next tRNA at the A site happens before translocation, peptide bond formation between the A-site tRNA and the growing chain in the P site happens prior to translocation, and the deacylated tRNA exits from the E site after translocation.

Translocation is the step in elongation where the ribosome moves along the mRNA by one codon, shifting the tRNAs from the A site to the P site and from the P site to the E site. This movement clears the A site for the next aminoacyl-tRNA to enter and keeps the reading frame aligned with the mRNA. The other steps occur in the cycle at different points: decoding the next tRNA at the A site happens before translocation, peptide bond formation between the A-site tRNA and the growing chain in the P site happens prior to translocation, and the deacylated tRNA exits from the E site after translocation.