Which enzymes 'charge' tRNAs with their amino acids?

Which enzymes 'charge' tRNAs with their amino acids?

• A. RNA polymerase
• B. Ligases
• C. Helicases
• D. Aminoacyl-tRNA synthetases

Answer: (D)

The essential idea is that tRNA charging is done by aminoacyl-tRNA synthetases. These enzymes specifically recognize each amino acid and its matching tRNA, then catalyze two steps: first, activation of the amino acid by ATP to form aminoacyl-AMP; second, transfer of the activated amino acid to the 3' end of the tRNA to make aminoacyl-tRNA. This pairing ensures the correct amino acid will be incorporated during translation according to the tRNA’s anticodon. Each amino acid generally has its own synthetase, and some synthetases have editing capabilities to prevent mischarging, which helps maintain translation fidelity. By contrast, RNA polymerase transcribes RNA, ligases join molecules, and helicases unwind nucleic acids; none of these attach amino acids to tRNA.

The essential idea is that tRNA charging is done by aminoacyl-tRNA synthetases. These enzymes specifically recognize each amino acid and its matching tRNA, then catalyze two steps: first, activation of the amino acid by ATP to form aminoacyl-AMP; second, transfer of the activated amino acid to the 3' end of the tRNA to make aminoacyl-tRNA. This pairing ensures the correct amino acid will be incorporated during translation according to the tRNA’s anticodon. Each amino acid generally has its own synthetase, and some synthetases have editing capabilities to prevent mischarging, which helps maintain translation fidelity. By contrast, RNA polymerase transcribes RNA, ligases join molecules, and helicases unwind nucleic acids; none of these attach amino acids to tRNA.