Which of the Following Statements About Translation Elongation in Bacteria

Question

Which of the following statements about translation elongation in bacteria is TRUE?
A) Charged amino acids are escorted to the A site of the ribosome by an initiation factor.
B) The growing polypeptide chain is moved from the A site to the P site before peptide bond formation.
C) GTP hydrolysis occurs after moving the aminoacyl-tRNA into the A site and before peptide bond formation.
D) The entire peptidyl-tRNA is translocated from the P site to the A site during peptide bond formation.
E) The uncharged tRNA leaves from the E site as the ribosome moves one codon in the 5' direction.

Accepted Answer

GTP is hydrolyzed by the elongation factor EF-Tu after moving the aminoacyl-tRNA into the A site and before peptide bond formation. The correct sequence of events during translation elongation in bacteria is: 1) The charged aminoacyl-tRNA binds to the A site with the help of EF-Tu and GTP. 2) The ribosome catalyzes peptide bond formation between the amino acid in the P site and the aminoacyl-tRNA in the A site. 3) GTP is hydrolyzed by EF-Tu and the uncharged tRNA is released from the E site. 4) The ribosome translocates by one codon in the 5' direction, moving the peptidyl-tRNA from the A site to the P site and creating an empty A site for the next aminoacyl-tRNA. 5) EF-G (elongation factor G) promotes ribosome translocation and requires GTP hydrolysis.