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3 Μαρ 2021 · Gene activation The process of activation of a gene so that it is expressed at a particular time. This process is crucial in growth and development.
How different genes are expressed in different cell types. The big picture of eukaryotic gene regulation.
Activator proteins bind to regulatory sites on DNA nearby to promoter regions that act as on/off switches. This binding facilitates RNA polymerase activity and transcription of nearby genes.
We begin with the simplest example—an on-off switch in bacteria that responds to a single signal. Go to: The Tryptophan Repressor Is a Simple Switch That Turns Genes On and Off in Bacteria. The chromosome of the bacterium E. coli, a single-celled organism, consists of a single circular DNA molecule of about 4.6 × 10 6 nucleotide pairs.
Download scientific diagram | Molecular mechanism of gene activation and repression. Gene activation and repression are regulated by acetylation of core histones.
Direct Gene Activation. Receptors that can directly influence gene expression are termed nuclear receptors. Located within the cytosol or nucleus, nuclear receptors are the target of steroid and thyroid hormones that are able to pass through the cell membrane.
Gene activation and inactivation are complicated, multistep, and tightly controlled molecular mechanisms. Increasingly it is being recognized that the promoter CpG island of a silenced gene is occupied by a polycomb group complex that modulates chromatin remodeling.
