what are the functional sites of a ribosome
Ribosomes are composed of two subunits, one small and one large. Four binding sites are located on the ribosome, one for mRNA and three for tRNA. The three tRNA sites are labeled P, A, and E. The P site, called the peptidyl site, binds to the tRNA holding the growing polypeptide chain of amino acids.The A site (acceptor site), binds to the aminoacyl tRNA, which holds the new amino acid to be added to the polypeptide chain.The E site (exit site), serves as a threshold, the final transitory step before a tRNA now bereft of its amino acid is let go by the ribosome.igure %: Amino Acid. When amino acids are transferred from the aminoacyl tRNA in the A site to the growing protein chain attached to the P site, they are transferred in a specific orientation so that the chain grows by adding amino acids to the carboxyl, not nitrogen, end of the chain.