Final answer:
The ribosome's large subunit contains peptidyl transferase, an RNA molecule with enzymatic properties known as a ribozyme, which catalyzes the formation of peptide bonds in the second step of protein elongation.
Step-by-step explanation:
The catalytic activity necessary for bond formation during the elongation step 2 of protein synthesis is a property of the peptidyl transferase in the large subunit of the ribosome. Hence, the ribosome acts as a ribozyme, which is a type of RNA that exhibits enzymatic properties. The peptidyl transferase is crucial for facilitating the formation of peptide bonds between amino acids during protein synthesis. This enzymatic activity adds new amino acids to the growing polypeptide chain, expanding the protein as specified by the mRNA template.