During elongation, where does the incoming aminoacyl-tRNA bind?

During elongation, where does the incoming aminoacyl-tRNA bind?

• A. E site
• B. A site
• C. P site
• D. Start site

Answer: (B)

During elongation, the ribosome has three tRNA binding pockets, and the incoming aminoacyl-tRNA binds at the A site. This site is designed to accept the next charged tRNA whose anticodon matches the mRNA codon currently being read, ensuring the correct amino acid is added to the growing chain. After binding, the ribosome forms a peptide bond between the new amino acid and the chain on the tRNA in the P site, then translocates so the A-site tRNA moves to the P site and the deacylated tRNA exits from the E site. The start site is used during initiation, not elongation.

During elongation, the ribosome has three tRNA binding pockets, and the incoming aminoacyl-tRNA binds at the A site. This site is designed to accept the next charged tRNA whose anticodon matches the mRNA codon currently being read, ensuring the correct amino acid is added to the growing chain. After binding, the ribosome forms a peptide bond between the new amino acid and the chain on the tRNA in the P site, then translocates so the A-site tRNA moves to the P site and the deacylated tRNA exits from the E site. The start site is used during initiation, not elongation.