During translation, which stage involves hydrogen bonds forming between the mRNA codon in the A site and its anticodon on the incoming tRNA?

During translation, which stage involves hydrogen bonds forming between the mRNA codon in the A site and its anticodon on the incoming tRNA?

• A. Initiation
• B. Translocation
• C. Termination
• D. Elongation

Answer: (D)

During elongation the ribosome decodes each mRNA codon as a new aminoacyl-tRNA enters the A site. The anticodon of that tRNA must base-pair with the codon, and those hydrogen bonds between codon and anticodon ensure the correct tRNA is selected before a peptide bond forms. Once the correct tRNA is bound, the ribosome catalyzes transfer of the growing polypeptide from the tRNA in the P site to the amino acid on the tRNA in the A site, then translocation shifts the ribosome to reveal the next codon. Initiation sets up the start codon and initiator tRNA at the P site, and termination occurs at a stop codon with release factors, so the codon–anticodon pairing in the A site happens specifically during elongation.

During elongation the ribosome decodes each mRNA codon as a new aminoacyl-tRNA enters the A site. The anticodon of that tRNA must base-pair with the codon, and those hydrogen bonds between codon and anticodon ensure the correct tRNA is selected before a peptide bond forms. Once the correct tRNA is bound, the ribosome catalyzes transfer of the growing polypeptide from the tRNA in the P site to the amino acid on the tRNA in the A site, then translocation shifts the ribosome to reveal the next codon. Initiation sets up the start codon and initiator tRNA at the P site, and termination occurs at a stop codon with release factors, so the codon–anticodon pairing in the A site happens specifically during elongation.