Which enzyme charges tRNA with its amino acid?

• A. Aminoacyl-tRNA synthetase
• B. DNA polymerase
• C. Ribosomal RNA polymerase
• D. Peptidyl transferase

Answer: (A)

Charging a tRNA with its amino acid is done by an aminoacyl-tRNA synthetase. This enzyme is specific for one amino acid and its matching tRNA, pairing them correctly. It uses energy from ATP to activate the amino acid, forming aminoacyl-AMP, and then transfers the amino acid to the tRNA’s 3′ end, producing aminoacyl-tRNA. This charged tRNA is ready to deliver the amino acid to the growing protein during translation, guided by the codon-anticodon interaction in the ribosome. Other enzymes listed have different roles: DNA polymerase builds DNA, RNA polymerase transcribes RNA, and peptidyl transferase helps form peptide bonds but does not attach amino acids to tRNA.