operon defined in 1951 yearoperon - operon;
operon - Group of closely linked genes responsible for the synthesis of a group of enzymes functionally related as members of one enzyme system; the activity of this group of genes in synthesizing messenger RNA being switched on or off by a single operator gene, which is also a part of the operon, but specializing in this controlling function. The genes controlled by the operator are called structural genes. The operator gene is itself controlled in one of two ways. Either it is switched off by a represser substance, which is produced by a regulator gene (not part of the operon) and which can be inactivated by some metabolite or signal substance (an effector) coming from elsewhere in the cell or from outside the cell; so that the presence of the effector results in the operon becoming active. Or it is switched off by a represser which is a combination of a substance (itself inactive) from the regulator gene with an effector from elsewhere; so that the presence of the effector results in the operon becoming inactive. Operon systems are concerned in the control of gene activity in bacteria, as in the formation of adaptive enzymes; and may be concerned in other organisms.
near operon in Knolik
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