Promoters are near the genes they transcribe, on the same strand of DNA and upstream.
Overview[change | change source]
For the transcription to take place, the enzyme that makes RNA, known as RNA polymerase, must attach to the DNA near a gene.
Promoters contain specific DNA sequences which give the RNA polymerase a binding site. There are also a number of proteins which help this process along, or which stop it happening. The whole thing is called the regulation of gene expression.
- In bacteria
- The promoter is recognized by RNA polymerase and an associated protein.
- In eukaryotes
- The process is more complicated, and at least seven different factors are necessary for the binding of an RNA polymerase II to the promoter.
Promoters are critical elements which work in concert with other regulatory regions. Together they adjust the level of transcription of a gene. So, genes get switched on when they are needed, and switched off when they are not. When they are on, they get adjusted up or down as needed.
References[change | change source]
- "Analysis of biological networks: transcriptional networks - promoter sequence analysis". Tel Aviv University. http://www.cs.tau.ac.il/~roded/courses/bnet-a06/lec11.pdf. Retrieved 30 December 2012.