Summary
The enzyme that builds an RNA strand complementary to the template DNA during transcription.
In depth
Bacteria use one polymerase with a sigma factor that recognises promoters. Eukaryotes use RNA polymerase I (rRNA), II (mRNA and many small RNAs) and III (tRNA and 5S rRNA). Unlike DNA polymerase, it needs no primer.
α-amanitin from death cap mushrooms blocks RNA polymerase II.
Unlike DNA polymerase, RNA polymerase needs no primer and has less proofreading, giving an error rate around 1 in 100,000. The enzyme is a molecular machine with a clamp, a bridge helix and a trigger loop; the bacterial core enzyme has five subunits and the sigma factor guides it to promoters. In bacteria, different sigma factors turn on gene sets, for example for heat shock or sporulation.
Pol II has a long C-terminal domain tail that is phosphorylated at different stages, coordinating capping, splicing and termination. Mitochondria and chloroplasts have their own polymerases, related to those of bacteria or phages.
Example: poliovirus makes RNA from RNA using an RNA-dependent RNA polymerase, which is why such viruses mutate so fast.
Frequently asked questions
What is RNA Polymerase?
The enzyme that builds an RNA strand complementary to the template DNA during transcription.
Which area of biology covers RNA Polymerase, and how advanced is it?
RNA Polymerase is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Transcription, Promoter, Initiation, Elongation, Termination.
Can you give an example of RNA Polymerase?
Rifampicin treats tuberculosis by blocking bacterial RNA polymerase.
What should I learn before RNA Polymerase?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to RNA Polymerase. Intermediate topics assume the Beginner vocabulary.
What topics are related to RNA Polymerase?
The closest topics to RNA Polymerase are Transcription, Promoter, Initiation, Elongation, Termination, DNA Replication. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand RNA Polymerase?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for RNA Polymerase. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is RNA Polymerase different from Transcription?
RNA Polymerase: The enzyme that builds an RNA strand complementary to the template DNA during transcription. Transcription: The process of making an RNA copy of a gene using DNA as a template. Read both side by side and note what each one explains.
How should I study RNA Polymerase step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Transcription and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.