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The stability of the final gene product, whether it is RNA or protein, also contributes to the expression level of the gene—an unstable product results in a low expression level. In general gene expression is regulated through changes [ 47 ] in the number and type of interactions between molecules [ 48 ] that collectively influence ...
A measurement of the amount of gene product is sometimes used to infer how active a gene is. Abnormal amounts of gene product can be correlated with disease-causing alleles, such as the overactivity of oncogenes, which can cause cancer. [1] [2] A gene is defined as "a hereditary unit of DNA that is required to produce a functional product". [3]
In the budding yeast Saccharomyces cerevisiae the number of essential genes is slightly higher, at 1000 genes (~20% of their genes). [110] Although the number is more difficult to measure in higher eukaryotes, mice and humans are estimated to have around 2000 essential genes (~10% of their genes). [ 111 ]
A regulator gene may encode a protein, or it may work at the level of RNA, as in the case of genes encoding microRNAs. An example of a regulator gene is a gene that codes for a repressor protein that inhibits the activity of an operator (a gene which binds repressor proteins thus inhibiting the translation of RNA to protein via RNA polymerase). [1]
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). Sophisticated programs of gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental ...
Cis-regulatory DNA sequences that are located in DNA regions distant from the promoters of genes can have very large effects on gene expression, with some genes undergoing up to 100-fold increased expression due to such a cis-regulatory sequence. [3] These cis-regulatory sequences include enhancers, silencers, insulators and tethering elements. [4]
Pseudogenes are usually characterized by a combination of similarity or homology to a known gene, together with a loss of some functionality. That is, although every pseudogene has a DNA sequence that is similar to some functional gene, they are usually unable to produce functional final protein products. [1]
Most genes considered master regulators code for transcription factor proteins, which in turn alter the expression of downstream genes in the pathway. [1] Canonical examples of master regulators include Oct-4 (also called POU5F1), SOX2 , and NANOG , all transcription factors involved in maintaining pluripotency in stem cells . [ 1 ]