Final answer:
The active site during elongation is made up of regions from the A and P subunits of the ribosome.
Step-by-step explanation:
The active site during elongation is made up of regions from two subunits: the A (aminoacyl) site and the P (peptidyl) site. The A site binds incoming charged aminoacyl tRNAs, while the P site binds charged tRNAs carrying amino acids that have formed peptide bonds with the growing polypeptide chain. These two subunits work together to allow the addition of new amino acids to the polypeptide chain during elongation.