Amino acid is attached to which site of tRNA?

The correct answer is Option (2) → 3′ end

tRNA is the adapter molecule of translation. On one side it reads the codon of mRNA; on the other side it carries the matching amino acid. Its secondary structure looks like a clover-leaf.

Option (1) Anticodon loop — Incorrect. The anticodon loop has bases complementary to the codon on mRNA. It reads the code; it does not hold the amino acid.

Option (2) 3′ end — Correct. The amino acid binds at the amino acid acceptor end of the tRNA, which is its 3′ end. The tRNA is first charged with its amino acid here, using energy from ATP.

Option (3) 5′ end — Incorrect. The 5′ end lies beside the acceptor end, but the amino acid is not attached to it.

Option (4) D-loop — Incorrect. The D-loop is one of the side loops of the clover-leaf. It helps the tRNA fold into shape and does not carry the amino acid.

NCERT Extract:
tRNA – the Adapter Molecule – “… tRNA has an anticodon loop that has bases complementary to the code, and it also has an amino acid acceptor end to which it binds to amino acids. tRNAs are specific for each amino acid (Figure 5.12). For initiation, there is another specific tRNA that is referred to as initiator tRNA. There are no tRNAs for stop codons. In figure 5.12, the secondary structure of tRNA has been depicted that looks like a clover-leaf.”