Describe the structure and function of tRNA during translation.

• A. tRNA has no anticodon and carries amino acids; it delivers amino acids.
• B. tRNA has an anticodon that base-pairs with mRNA codon and a 3' CCA end that carries a specific amino acid; it delivers amino acids to the ribosome during elongation.
• C. tRNA is a component of the ribosome and catalyzes peptide bonds.
• D. tRNA binds DNA to bring amino acids to the ribosome.

Answer: (B)

The key idea is that tRNA serves as the molecular adaptor that both recognizes the genetic code and delivers the correct amino acid to the growing protein chain. tRNA has an anticodon that base-pairs with a specific codon on the mRNA, ensuring the right amino acid is added for each codon. It also has a 3' CCA end that carries a specific amino acid, attached by aminoacyl-tRNA synthetases, so each tRNA is charged with the correct amino acid before it participates in translation. During elongation, the charged tRNA brings its amino acid to the ribosome, where the anticodon pairing positions the amino acid for incorporation into the polypeptide, while the ribosome catalyzes the peptide bond formation. tRNA is not a ribosome component and does not catalyze peptide bonds itself, nor does it bind DNA.