Genetics & Inheritance MCAT Practice Question
A student studies the lac operon in E. coli and learns about a mutation that prevents the repressor protein from binding to the operator region. The student predicts that in the absence of lactose, the structural genes of the lac operon will be constitutively expressed. Is this prediction correct, and what is the molecular basis?
Answer choices
- ANo, because the repressor must be activated by lactose to function
- BNo, because RNA polymerase cannot access the promoter without the repressor
- CYes, because the repressor cannot bind the operator to block transcriptionCorrect answer
- DYes, but only if the CAP-cAMP complex is absent
- ENo, because lactose must be present to induce the operon regardless of repressor function
- FYes, but only if the sigma factor is able to recognize the promoter sequence
See the full explanation
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