10:12 LTE Quiz 5: Attempt 1 Question 3 Suppose you have a bacterial strain with
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10:12 LTE Quiz 5: Attempt 1 Question 3 Suppose you have a bacterial strain with the following genotype for the lac operon. How is this lac operon regulated? I- P+ O+ Z+Y The operon is non inducible, and lacz is 1) never transcribed, even in the presence of lactose The operon is constitutive, and lacZ is transcribed even when lactose is absent. The operon is inducible, and lacZ is transcribed only in the presence o f lactose The operon is repressible, and lacZ is only expressed in the absence of lactose. The operon is constitutive, and both lacz and lacY are expressed all the time. Question 4 0 of 10 completed Save for Later SubmitExplanation / Answer
In the given genotype, lactose is absent and its not defined that glucose is absent or present. Thus, if lactose is absent then operon will surely be Off, because repressor will bind to the lac promoter and prevent the RNA polymerase from binding to it, inhibiting the expression of the enzymes.
Lac Z is only expressed when lactose is present, otherwise genetic expression of the structural gene lac Z is blocked.
Option 1 seems to be the right answer. Because as per lac operon explanations above, as lactose is absent thus operon should be non inducible, the second condition says that lac Z is never transcribed in the presence of lactose signifies that glucose is present, thus lac Z has not been transcribed.
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