Final answer:
Bacteria have only one RNA polymerase, while eukaryotes have multiple RNA polymerases for different types of RNA transcription.
Step-by-step explanation:
In bacteria, there is only one RNA polymerase that is responsible for transcribing all of their genes.
In E. coli, the RNA polymerase is composed of five subunits, with two of them being identical.
The polymerase core enzyme consists of four subunits: α, α, β, and β'.
These subunits have specific roles in assembling the polymerase on the DNA, binding to the ribonucleoside triphosphate that will become part of the mRNA molecule, and binding to the DNA template strand.
Additionally, there is a fifth subunit, σ, involved in transcription initiation, which ensures the polymerase begins synthesizing mRNA from the appropriate initiation site.
Unlike bacteria, eukaryotes have multiple RNA polymerases that catalyze the transcription of different types of RNA molecules.
For example, RNA polymerase II is responsible for transcribing messenger RNA (mRNA).
In 2006, Roger Kornberg was awarded the Nobel Prize in Medicine for his discovery of the role of RNA polymerase II and other proteins involved in eukaryotic mRNA transcription.