Which site binds the next incoming aminoacyl-tRNA complex?

Which site binds the next incoming aminoacyl-tRNA complex?

• A. E site
• B. A site
• C. P site
• D. B site

Answer: (B)

In translation elongation, the next aminoacyl-tRNA complex binds at the A site of the ribosome. This site is the docking point where the tRNA, carrying its new amino acid, pairs its anticodon with the mRNA codon currently exposed in the ribosome. If the pairing is correct, the amino acid on this tRNA is joined to the growing polypeptide chain, transferring from the tRNA in the P site via peptide bond formation. After this, the ribosome shifts so the peptidyl-tRNA moves to the P site and the now-empty tRNA exits through the E site, leaving the A site free for the next aminoacyl-tRNA. The E site is the exit site for deacylated tRNA, and there is no B site on the ribosome.

In translation elongation, the next aminoacyl-tRNA complex binds at the A site of the ribosome. This site is the docking point where the tRNA, carrying its new amino acid, pairs its anticodon with the mRNA codon currently exposed in the ribosome. If the pairing is correct, the amino acid on this tRNA is joined to the growing polypeptide chain, transferring from the tRNA in the P site via peptide bond formation. After this, the ribosome shifts so the peptidyl-tRNA moves to the P site and the now-empty tRNA exits through the E site, leaving the A site free for the next aminoacyl-tRNA. The E site is the exit site for deacylated tRNA, and there is no B site on the ribosome.