A 40 year old female patient complains of burning sensation during micturition. Patient gives history of recurrent urinary tract infection. Urine culture reveals presence of E.coli. Which of the following enzyme synthesizes all the RNAs in the isolated organism in this patient?
First, I need to recall the enzymes involved in RNA synthesis in bacteria. In eukaryotes, there are different RNA polymerases for mRNA, rRNA, and tRNA, but bacteria have a single RNA polymerase that does all these. The core concept here is the difference between prokaryotic and eukaryotic RNA polymerases.
The correct answer should be RNA polymerase. E. coli, being a prokaryote, uses a single RNA polymerase enzyme for transcribing all types of RNA. The eukaryotic counterpart has three different polymerases, but that's not the case here.
Looking at the options, even though they aren't listed, typical distractors might include DNA polymerase, which synthesizes DNA, or specific eukaryotic RNA polymerases like RNA Pol I, II, III. Also, other enzymes like peptidyl transferase involved in translation could be a wrong option.
The clinical pearl here is remembering that prokaryotes have one RNA polymerase, while eukaryotes have three. This is a high-yield fact for microbiology and molecular biology exams.
**Core Concept**
The question tests knowledge of prokaryotic RNA synthesis mechanisms. In *E. coli*, a single RNA polymerase enzyme is responsible for transcribing all RNA types (mRNA, rRNA, tRNA), unlike eukaryotes which have multiple specialized RNA polymerases.
**Why the Correct Answer is Right**
*Escherichia coli* uses a single **RNA polymerase** (composed of core enzyme and sigma factor) to transcribe all RNA molecules. This enzyme binds to promoter regions, unwinds DNA, and catalyzes RNA synthesis via phosphodiester bond formation. Prokaryotic RNA polymerase lacks the complexity of eukaryotic counterparts (Pol I/II/III), streamlining gene expression in bacteria.
**Why Each Wrong Option is Incorrect**
**Option A:** DNA polymerase synthesizes DNA during replication, not RNA.
**Option B:** Peptidyl transferase is an enzymatic activity of the ribosome during translation, not RNA synthesis.
**Option C:** Eukaryotic RNA polymerases (e.g., Pol II) are absent in prokaryotes like *E. coli*.
**Clinical Pearl / High-Yield Fact**
Prokaryotes (e.g., *E. coli*) use **one RNA polymerase** for all RNA synthesis. Eukaryotes require **three distinct RNA polymerases** (Pol I, II, III) for rRNA, mRNA, and tRNA synthesis, respectively. This distinction is critical for antimicrobial drug targets and exam questions.
**Correct Answer: C. RNA polymerase**