Final answer:
The initiator tRNA uniquely binds to the P site during the initiation of translation. During elongation, the incoming charged tRNAs bind to the A site, and following peptide bond formation and ribosome translocation, exit through the E site.
Step-by-step explanation:
The initiator tRNA is special because it is the only tRNA that can initially bind at the P site in the ribosome. This creates an initiation complex with a free A site ready to accept the tRNA corresponding to the first codon after the AUG start codon. During elongation in translation, to which ribosomal site does an incoming charged tRNA molecule bind? The correct answer is A site, as this is the functional site of an intact ribosome that binds incoming charged aminoacyl tRNAs during the elongation phase of protein synthesis. The process involves peptide bond formation, with the ribosome translocating to allow tRNAS to shift from the A site to the P site, and finally the tRNA exits via the E site.