Question

Which of the following occurs as a result of translocation? O The tRNA that was in the P site moves into the E site. O The tRNA that was in the E site moves into the P site. The tRNA that was in the E site moves into the A site. O The tRNA that was in the P site moves into the A site. O The tRNA that was in the A site moves into the E site.

Answer 1

Ans-{a} The tRNA that was in the P site moves into the E site.

The new peptidyl-tRNA in the A-site is translocated to the P-site and the tRNA that was in the P-site moves into E site as the ribosome moves exactly three nucleotides along the mRNA molecule, going in the 5-3 direction.this step is mediated by the elongation factor EF-G {also called translocated} and is driven by splitting a GTP to GDP. This action release the uncharged tRNA from the P site and transfers the newly formed peptidyl-tRNA from the A-site to the P-site.The uncharged tRNA in the P-site moves to a third position, the E or exit site of ribosome.{Each ribosome has three aminoacyl -tRNA binding site -A site, P-site, and E site, E site transiently binds the outgoing deacetylated tRNA},