Question

What is special about the P site of a ribosome?

A) It contains the enzyme that catalyzes formation of a peptide bond.
B) It has the binding site for mRNA.
C) It holds the tRNA with the most recent amino acid that has been added to the polypeptide chain.
D) It holds the tRNA with the next amino acid to be added to the polypeptide chain.
E) It causes the ribosome to attach to the endoplasmic reticulum.

Answer 1

The P site of a ribosome holds the tRNA with the most recent amino acid added to the polypeptide chain during translation elongation.

Step-by-step explanation:

The P site of a ribosome is special because it holds the tRNA with the most recent amino acid that has been added to the polypeptide chain.

During translation elongation, a charged tRNA binds to the ribosome's A site and a peptide bond is formed between the amino acids carried by the tRNA in the P site and the tRNA in the A site. The P site tRNA then becomes the tRNA with the most recent amino acid that has been added to the polypeptide chain.

Subsequently, the ribosome translocates, moving the tRNA in the P site to the E site and allowing the A site to be available for the next tRNA with the next amino acid to be added.