rokaryoticgeneregulation：原核基因表達調(diào)控-閱讀頁
2025-01-27 08:18本頁面
【正文】 usually off。 2022 Pearson Education, Inc. publishing as Benjamin Cummings Lac Operon Animation content/ Copyright 169。 2022 Pearson Education, Inc. publishing as Benjamin Cummings Positive Gene Regulation ? Some operons are also subject to positive control through a stimulatory activator protein, such as catabolite activator protein (CAP) ? When glucose (a preferred food source of E. coli ) is scarce, the lac operon is activated by the binding of CAP ? When glucose levels increase, CAP detaches from the lac operon, turning it off LE 1823a DNA cAMP lacl CAPbinding site Promoter Active CAP Inactive CAP RNA polymerase can bind and transcribe Operator lacZ Inactive lac repressor Lactose present, glucose scarce (cAMP level high): abundant lac mRNA synthesized LE 1823b DNA lacl CAPbinding site Promoter RNA polymerase can’t bind efficiently Operator lacZ Inactive lac repressor Inactive CAP Lactose present, glucose present (cAMP level low): little lac mRNA synthesized Copyright 169。 2022 Pearson Education, Inc. publishing as Benjamin Cummings The Arabinose Operon A Composite of Negative amp。 2022 Pearson Education, Inc. publishing as Benjamin Cummings Regulatory gene Operator (part of the promoter) Promoter for the cluster of genes B, A, and D Application of Operons: Copyright 169。 3
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