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Regulation of gene expression by a hormone receptor Diagram showing at which stages in the DNA-mRNA-protein pathway expression can be controlled. Regulation of gene expression, or gene regulation, [1] includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA).
A regulatory sequence is a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism. Regulation of gene expression is an essential feature of all living organisms and viruses.
In molecular biology and genetics, transcriptional regulation is the means by which a cell regulates the conversion of DNA to RNA (transcription), thereby orchestrating gene activity. A single gene can be regulated in a range of ways, from altering the number of copies of RNA that are transcribed, to the temporal control of when the gene is ...
Eukaryotes have a much larger genome and thus have different methods of gene regulation than in prokaryotes. All cells in a eukaryotic organism have the same DNA but are specified through differential gene expression, a phenomenon known as genetic totipotency. [7]
Two-component systems in eukaryotes likely originate from lateral gene transfer, often from endosymbiotic organelles, and are typically of the hybrid kinase phosphorelay type. [3] For example, in the yeast Candida albicans , genes found in the nuclear genome likely originated from endosymbiosis and remain targeted to the mitochondria . [ 31 ]
A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. [1] Activators are considered to have positive control over gene expression, as they function to promote gene transcription and, in some cases, are required for the transcription of genes to occur.
The Britten–Davidson model, [1] [2] also known as the gene-battery model, [3] is a hypothesis for the regulation of protein synthesis in eukaryotes.Proposed by Roy John Britten and Eric H. Davidson in 1969, the model postulates four classes of DNA sequence: an integrator gene, a producer gene, a receptor site, and a sensor site.
Eukaryotic transcription occurs within the nucleus where DNA is packaged into nucleosomes and higher order chromatin structures. The complexity of the eukaryotic genome necessitates a great variety and complexity of gene expression control. Eukaryotic transcription proceeds in three sequential stages: initiation, elongation, and termination. [1]