What is the Difference Between Prokaryotic and Eukaryotic RNA Polymerase?

The main difference between prokaryotic and eukaryotic RNA polymerase lies in the number of enzymes involved and the complexity of transcription in eukaryotes. Here are the key differences:

1. Number of RNA Polymerases: Prokaryotes have a single type of RNA polymerase, while eukaryotes have three main types of RNA polymerases (RNA polymerase I, II, and III).
2. Functions: In eukaryotes, each RNA polymerase is responsible for transcribing specific classes of genes. RNA polymerase I transcribes ribosomal RNA (rRNA) genes, RNA polymerase II transcribes messenger RNA (mRNA) genes, and RNA polymerase III transcribes small RNA genes, such as genes for transfer RNAs (tRNAs). Prokaryotic RNA polymerase, on the other hand, is responsible for transcribing all genes in bacteria.
3. Subunits: Prokaryotic RNA polymerase contains five subunits, including four catalytic subunits and a single regulatory subunit known as sigma (σ). In eukaryotes, the RNA polymerases have different numbers and types of subunits.
4. Transcription Factors and co-factors: In prokaryotes, transcription factors and transcription-mediated complexes guide the RNA polymerase during the transcription process. In eukaryotes, RNA polymerases require interaction with additional proteins to specifically initiate transcription.

Despite these differences, both prokaryotic and eukaryotic RNA polymerases share some common features, such as being large proteins, having a sigma factor that initiates transcription, and needing transcription factors to regulate the steps of transcription.

Comparative Table: Prokaryotic vs Eukaryotic RNA Polymerase

The main difference between prokaryotic and eukaryotic RNA polymerase lies in the number of enzymes involved and their functions. Here is a summary of the differences:

Despite these differences, both prokaryotic and eukaryotic RNA polymerases share some similarities:

• Both are DNA-directed RNA polymerases.
• Before transcription, transcription factors bind to the promoter region to initiate the unwinding of DNA, recruiting RNA polymerase to the DNA template.
• RNA polymerases can be either multisubunit enzymes or single subunit enzymes.

In summary, prokaryotic RNA polymerase is a single enzyme with five subunits that synthesizes all types of RNA, while eukaryotic RNA polymerase comprises three main types, each with 10 or more subunits, and has a more complex transcription process involving distinct transcription factors.