2. What is RNA
polymerase?
RNA polymeras is an enzymes that
produce RNA in the cell. It is an enzyme that
is responsible for coping a DNA sequence
into RNA sequence , during the process of
transcription .
3. Prokaryotic RNA Polymerase Eukaryotic RNA Polymerase
•Consists of four sub units and a
sigma factor.
• There are five different types
of RNA polymerase.
•Only a single type of RNA
polymerase occurs.
•Five types of RNA polymerase
occurs.
•The core enzyme contains five
subunits.
•Every type contains 10-12
subunits.
•Size : Around 400 kDa •Size: Around 500 kDa
Some differences between Prokaryotic and
Eukaryotic RNA Polymerase
4. Types of RNA Polymerase
RNA Polymerase 1:
•This enzyme is located in the nucleolus of the cell.
•It is a specialized nuclear substructure where the ribosomal RNA
(rRNA) is synthesized by transcription and assembled into
ribosomes.
RNA Polymerase 11:
•It functions by synthesizing all proteins that code for the nuclear
pre-mRNAs in eukaryotic cells (mRNAs in prokaryotic cells).
•It is responsible for transcribing most of the eukaryotic genes .
5. RNA Polymerase 111:
•It is located in the nucleus.
•Its function is to transcribe transfer RNA (tRNA), ribosomal RNA
(rRNA), and other small RNAs.
RNA Polymerase 1V & V:
•In Plants, the RNA polymerase is found in the chloroplast (plastids)
and mitochondria, encoded by the mitochondrial DNA.
•Their function is to catalyze specific transcription of organelle
genes.
