Transcription factors are proteins that recognise short DNA sequences, a few letters long. They sit on enhancers, switches near or far from a gene, and help RNA polymerase start at the gene’s promoter; other factors keep genes off. Established: Replicated many times; textbook knowledge.
The idea was first worked out in bacteria, which switch on the genes for digesting a sugar only when that sugar is around (Jacob & Monod 1961). Plants use factors to decide when to flower, and humans have more than 1,600 of them (Lambert et al. 2018). Each cell type makes its own mix, so each switches on its own genes.
On, then off again. Polymerase starts again and again, making mRNA copies in bursts. When the factor lets go, the gene falls quiet. Each cell type makes its own set of factors, so each switches on its own genes.
In my research: The factors and complexes that control genes in early development →
Sources
- Jacob F, Monod J (1961) Genetic regulatory mechanisms in the synthesis of proteins. Journal of Molecular Biology 3:318–356. doi:10.1016/S0022-2836(61)80072-7
- Lambert SA, et al. (2018) The human transcription factors. Cell 172:650–665. doi:10.1016/j.cell.2018.01.029