Final answer:
The catalytic center of RNA polymerase in prokaryotes consists of two subunits, the β and β'. These subunits perform distinct functions essential for transcription, with one binding the ribonucleoside triphosphate for mRNA synthesis and the other binding the DNA template strand.The correct option is D.
Step-by-step explanation:
The catalytic center of RNA polymerase (RNAP) in prokaryotes, such as E. coli, is formed by the β and β' subunits. These two subunits are part of the polymerase core enzyme and each plays a specific role in transcription.
The β subunit binds to the ribonucleoside triphosphate that will become part of the new mRNA molecule, while the β' subunit binds the DNA template strand.
Altogether, the RNA polymerase in E. coli is composed of five polypeptide subunits including two α subunits, one β subunit, one β' subunit, and the ω (sigma) subunit which is only involved in transcription initiation. Hence, the answer to the question is D. Beta and beta prime.