catabolite repression

ca·tab·o·lite re·pres·sion

the decreased expression of an operon because of elevated levels of a catabolite of a biochemical pathway.

catabolite repression

REPRESSION of certain INDUCIBLE ENZYME systems by the presence of specific carbon sources, such as GLUCOSE, that the organism prefers to metabolize. For example, in bacteria, EXPRESSION of the LAC OPERON, concerned with the enzymes for the breakdown of LACTOSE, is repressed in the presence of glucose, even though inducers of the operon are available. When the glucose is used up, expression of the lactose operon can be induced. Catabolite repression is important to the efficient running of the cell, because glucose can be metabolized directly in GLYCOLYSIS without the need to expend energy inducing the synthesis of those enzymes required to metabolize the lactose. See also OPERON MODEL.

单词	catabolite repression
释义	catabolite repression catabolite repression [kə′tab·ə‚līt ri′presh·ən] (biochemistry) An intracellular regulatory mechanism in bacteria whereby glucose, or any other carbon source that is an intermediate in catabolism, prevents formation of inducible enzymes. catabolite repression ca·tab·o·lite re·pres·sion the decreased expression of an operon because of elevated levels of a catabolite of a biochemical pathway. catabolite repression REPRESSION of certain INDUCIBLE ENZYME systems by the presence of specific carbon sources, such as GLUCOSE, that the organism prefers to metabolize. For example, in bacteria, EXPRESSION of the LAC OPERON, concerned with the enzymes for the breakdown of LACTOSE, is repressed in the presence of glucose, even though inducers of the operon are available. When the glucose is used up, expression of the lactose operon can be induced. Catabolite repression is important to the efficient running of the cell, because glucose can be metabolized directly in GLYCOLYSIS without the need to expend energy inducing the synthesis of those enzymes required to metabolize the lactose. See also OPERON MODEL.
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