RNA polymerase

Definition

RNA polymerase is an enzyme that synthesizes RNA from a DNA template during transcription. It plays a crucial role in gene expression by creating mRNA, tRNA, and rRNA molecules.

5 Must Know Facts For Your Next Test

1. There are three main types of RNA polymerases in eukaryotes: RNA polymerase I, II, and III, each responsible for transcribing different types of RNA.
2. In prokaryotes, a single type of RNA polymerase synthesizes all types of RNA.
3. The sigma factor is required for the initiation of transcription in prokaryotes by helping the RNA polymerase recognize the promoter region.
4. RNA polymerase does not require a primer to start synthesis; it initiates RNA synthesis de novo.
5. The termination of transcription can occur via rho-dependent or rho-independent mechanisms in bacteria.

Review Questions

• What role does the sigma factor play in prokaryotic transcription?
• How many types of RNA polymerase are there in eukaryotes and what are their functions?
• Describe the difference between rho-dependent and rho-independent termination mechanisms.

Related terms

DNA Polymerase:

An enzyme that synthesizes DNA molecules from deoxyribonucleotides during DNA replication.

Transcription Factor: Proteins that control the rate of transcription by binding to specific DNA sequences.

Operon:

A functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter.