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754. A mutation in the Lac repressor protein prevents it from binding to lactose. Will the...

754. A mutation in the Lac repressor protein prevents it from binding to lactose. Will the Lac operon be expressed when lactose levels are high and glucose levels are low? Explain your reasoning.

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Answer #1

In this situation, lac operon will not be expressed ( repressed) even in presence of high lactose or low glucose level.

Explanation-

Normally Lac repressor binds at operator, repress the operon.

But when lactose is present, this lactose binds to repressor molecules ( repressor molecules has high affinity to lactose) , thus due to change in conformation repressor molecules are not able to bind operator site --- induction of lac operon.

But here Lac repressor domain which mediate its binding to lactose is mutated -- so  repressor will not bond to lactose-- and always bind to operator-- repress the lac operon or decreased expression of lac operon Gene's.

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