Initiation site

Definition

The initiation site is the specific location on DNA where transcription begins. It is typically marked by the +1 nucleotide, where RNA polymerase starts synthesizing RNA.

5 Must Know Facts For Your Next Test

1. The initiation site is situated immediately downstream of the promoter region.
2. In prokaryotes, the -10 and -35 consensus sequences in the promoter help position RNA polymerase at the initiation site.
3. The first nucleotide transcribed from the initiation site is complementary to the template strand of DNA.
4. Mutations at or near the initiation site can affect transcription efficiency and gene expression levels.
5. The sigma factor in prokaryotes plays a crucial role in recognizing and binding to the promoter to correctly position RNA polymerase at the initiation site.

Review Questions

Related terms

Promoter:

A DNA sequence upstream of a gene that provides a binding site for RNA polymerase to initiate transcription.

RNA Polymerase: An enzyme that synthesizes RNA from a DNA template during transcription.

Sigma Factor: A protein that associates with RNA polymerase and facilitates its binding to specific promoters in prokaryotes.