gene expression
gene expression The manifestation of the effects of a gene by the production of the particular protein, polypeptide, or type of RNA whose synthesis it controls. Individual genes can be ‘switched on’ (exert their effects) or ‘switched off’ according to the needs and circumstances of the cell at a particular time. A number of mechanisms are thought to be responsible for the control of gene expression; the Jacob–Monod hypothesis postulates the mechanism operating in prokaryotes (see operon). Control of gene expression is known to be more complicated in eukaryotes, which possess various control mechanisms not seen in prokaryotes. For example, the methylation of cytosine bases of specific genes in eukaryotic DNA is observed in cells in which the gene is not expressed; if DNA methylation is prevented by the use of inhibitory chemicals, this can cause certain genes to be expressed. In multicellular organisms, expression of the right genes in the right order at the right times is particularly crucial during embryonic development and cell differentiation. This involves subtle and complex interplay of chemical signals with the embryo's genes, in patterns that vary between different types of organism (see differentiation). Abnormalities of gene expression may result in the death of cells, or their uncontrolled growth, as in cancer. See also transcriptomics.
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Regulator Gene , regulatory gene In the operon theory of gene regulation, a gene that is involved in switching on or off the transcription of structural genes. When t… Operon , Operon
An operon is a genetic regulatory system found in prokaryotes and the bacterial viruses (bacteriophages ) that attack bacteria. It is a cluste… Dna Microarray , DNA microarrays are tools used to analyze and measure the activity of genes. Researchers can use microarrays and other methods to measure changes in… Methylation , DNA methylation is a mechanism used to regulate genes and protect DNA from some types of cleavage. It is one of the regulatory processes that are ref… Pseudogenes , Pseudogenes are defective copies of functional genes. These may be partial or complete duplicates derived from polypeptide-encoding genes or RNA gene… knockout , knockout A technique for inactivating a particular gene or genes within an organism or cell. Both single-celled and multicellular organisms can be ge…
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gene expression