BSC 310 Lecture Notes - Lecture 29: Chemotaxis, Cell Membrane, Histidine
22 Mar 2016
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Lecture 29- global control and the lac operon. Global control systems- regulatory mechanisms that respond to environmental signals by regulating the expression of many different genes (cid:1) Catabolite repression- mechanism of global control that decides between utilizing different available carbon sources (cid:1) Synthesis of enzymes to catabolize other sugars is repressed if glucose is present in environment. Ensures that the best available c and energy source is used first (cid:1) Dozens of catabolic operons are affected by catabolic repression, including enzymes for degrading lactose, maltose, and other common carbon sources (cid:1) (cid:1) (cid:1) Flagellar genes are also controlled by catabolite repression. Catabolite repression can result in 2 exponential growth phases. Diauxic growth- cells grow first on preferred c source, when it is depleted, go through a lag phase before growth resumes on another c source. Additional genes needed for c source utilization are also repressed until that c source is needed (cid:1) (cid:1) (cid:1)
