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B2. Consider E. coli cells, each having one of the following mutations: a) a mutant lac...

B2. Consider E. coli cells, each having one of the following mutations: a) a mutant lac operator (Oc locus) that cannot bind repressor. b) a mutant lac repressor (I- gene product) that cannot bind to the lac operator. c) a mutant lac repressor (the Is gene product) that cannot bind to lactose. d) a mutant lac promoter that cannot bind CAP + cAMP. What effect would each mutation have on the function of lac operon (assuming no glucose is present) (10 points).

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Answer #1

a, if repressor cant bind on operator, then constitutive expression of lac operon occur.

b,if regulatory gene produce defective repressor such that it cant bind to operator so constitutive expression of lac operon occur.

C,if lac repressor cant bind to lactose , then it will remain bound to operator even in presence of lactose and lac operon remain off even in presence of lactose.

D, cAMP+CAP increases expression of lac operon in presence of lactose , so if they don't bound then expression of lac operon gene will be less.

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