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Q. 1 PLEASE EXPLAIN If the lac permease is required to bring inducer into the cell,...

Q. 1 PLEASE EXPLAIN If the lac permease is required to bring inducer into the cell, and inducer is required to activate transcription of the lac operon, then how do E. coli ever turn on the lac operon even when lactose is around?

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E. coli ever turn on the lac operon even when lactose is around is by lac operon of E.coli contains genes involved in lactose metabolism. And it's expressed only when the lactose is present and the glucose is absent.The Two regulators turn the operon "on" and "off" in response to lactose and glucose levels: the lac repressor and catabolite activator protein (CAP).it should be noted that the Lactose operon expresses as long as the Lactose is present. When all lactose is converted into glucose and galactose, the reaction stops.And also when If glucose is present and lactose is absent, the lac repressor binds to the operator  both glregion.And if glucose and lactose are both present, lactose binds to the repressor and prevents it from binding to the operator region.This is how it works.

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