Question

What is the difference between the P-site and A-site of a ribosome?

Answer 1

Four binding sites are located on the ribosome, one for m-RNA and three for t-RNA. The three t-RNA sites are labelled P, A and E.

The P site, called the peptidyl site, binds to the t-RNA holding the growing polypeptide chain of amino acids.

A site bins to the aminoacyl t-RNA, which holds the new amino acid to be added to the polypeptide chain.