This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Ribosomes has following enzymatic activity? 
Select and explain. 
A. Peptidyl transferase, B. Peptidase, C. Aminoacyl tRNA synthetase, D. GTPase
A: Peptidyl transferase
Answer: A: Peptidyl transferase 
Explanation: The formation of peptide bonds is catalysed by peptidyl transferase, an activity intrinsic to the 23 S r-RNA of 50 S subunit in prokaryotes and 28 S r-RNA of 60 S subunit in eukaryotes. So, it is referred to as ribozyme & indicates a direct role of r-RNA in protein synthesis.