A partial diploid E. coli cell of lacI⁺ lacP^-lacO^c lacI⁺lacY⁺ / lacI^s lacP⁺lacO⁺ lacZ⁺ lacY^- will synthesize: A) both lacZ and lacY functional gene products in the absence of lactose. B) neither lacZ nor lacY functional gene products in the presence of lactose. C) both lacZ and lacY functional gene products in the presence of lactose. D) lacY but not a functional lacZ gene product in the absence of lactose. E) lacZ but not a functional lacY gene product in the absence of lactose.

Question

Quizplus · Accepted Answer

The lacI^s mutation produces a super-repressor that cannot be inactivated by lactose, preventing transcription of the lac operon regardless of lactose presence. The lacO^c mutation allows constitutive expression of lacY, but lacI^s prevents lacZ expression.

A Partial Diploid E