Final answer:
The active site of the peptidyl transfer center is found in the large subunit of the ribosome, specifically known as the 50S subunit in bacteria like E. coli, where peptidyl transferase catalyzes peptide bond formation.
Step-by-step explanation:
The active site of the peptidyl transfer center is located within the large subunit of the ribosome. In bacterial ribosomes, like those of E. coli, this large subunit is known as the 50S subunit. It is here that the peptidyl transferase, an RNA-based enzyme, catalyzes the formation of peptide bonds between amino acids during protein synthesis.
During the elongation phase of translation, the ribosome coordinates the movement of tRNAs through the A (aminoacyl), P (peptidyl), and E (exit) sites. The P site, which is part of the large subunit, holds the tRNA attached to the growing polypeptide chain, while the A site accommodates the incoming tRNA carrying the next amino acid to be added to the chain. The catalytic action of peptidyl transferase facilitates the bond formation between the amino group of the amino acid attached to the A-site tRNA and the carboxyl group of the amino acid attached to the P-site tRNA.