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Promoter (genetics)
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2: Repressor
3: Promoter
4: Operator
5: Lactose
6: lacZ, 7: lacY, 8: lacA.
Top: The transcription of the gene is turned off. There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making the mRNA encoding the lactase gene. Bottom: The gene is turned on. Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter and express the genes, which synthesize lactase. Eventually, the lactase will digest all of the lactose, until there is none to bind to the repressor. The repressor will then bind to the operator, stopping the manufacture of lactase.
In genetics, a promoter is a sequence of DNA to which proteins bind to initiate transcription of a single RNA transcript from the DNA downstream of the promoter. The RNA transcript may encode a protein (mRNA), or can have a function in and of itself, such as tRNA or rRNA. Promoters are located near the transcription start sites of genes, upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long, the sequence of which is highly dependent on the gene and product of transcription, type or class of RNA polymerase recruited to the site, and species of organism.[1][2]
- ^ Sharan R (4 January 2007). "Analysis of Biological Networks: Transcriptional Networks – Promoter Sequence Analysis" (PDF). Tel Aviv University. Retrieved 30 December 2012.
- ^ LaFleur TL, Hossain A, Salis HM (September 2022). "Automated model-predictive design of synthetic promoters to control transcriptional profiles in bacteria". Nature Communications. 13 (1): 5159. Bibcode:2022NatCo..13.5159L. doi:10.1038/s41467-022-32829-5. PMC 9440211. PMID 36056029.
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