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Multiple Choice
An aminoacyl-tRNA that enters the A site of the ribosome will next occupy which site?
A
R site
B
E site
C
P site
D
A site
Verified step by step guidance
1
Understand the structure and function of the ribosome during translation. The ribosome has three sites for tRNA binding: the A site (aminoacyl site), the P site (peptidyl site), and the E site (exit site).
Recognize the role of each site: The A site is where the aminoacyl-tRNA first binds, the P site is where the tRNA carrying the growing polypeptide chain resides, and the E site is where the tRNA exits the ribosome after its amino acid has been added to the chain.
Identify the sequence of tRNA movement through the ribosome: An aminoacyl-tRNA enters the A site first, then moves to the P site as the ribosome catalyzes the formation of a peptide bond between the amino acid on the tRNA in the A site and the growing polypeptide chain on the tRNA in the P site.
After the peptide bond formation, the ribosome translocates, moving the tRNA from the A site to the P site, and the tRNA that was in the P site moves to the E site to exit the ribosome.
Conclude that the next site occupied by the aminoacyl-tRNA after the A site is the P site, as it is involved in the elongation of the polypeptide chain.