DAT Bootcamp Molecular Genetics Practice Test 2026 - Free Molecular Genetics Practice Questions and Study Guide

During translation, the ribosome has three tRNA binding sites: A, P, and E. The growing polypeptide chain is held by the tRNA in the peptidyl-tRNA occupying the P site. The A site is where the next aminoacyl-tRNA enters, and after the peptide bond forms, translocation moves the peptidyl-tRNA into the P site while the now-empty tRNA exits from the E site. Because the growing chain remains attached to the tRNA in the P site, that is the location carrying the growing polypeptide. There isn’t a true M site on the ribosome.