Transcription and Translation · USMLE Step 1

What energy source is directly used by aminoacyl-tRNA synthetase during tRNA charging?

  1. GTP
  2. ATP
  3. CTP
  4. No energy required — spontaneous
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Correct answer: ATP

Aminoacyl-tRNA synthetases use ATP hydrolysis to form a high-energy ester bond between the tRNA 3′ end and its specific amino acid. This “charging” is energy-dependent.

Difficulty: Medium Question 13 of 22

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