Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If a researcher moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following processes would likely occur when the cell is exposed to lactose?
A) The inducer will no longer bind to the repressor.
B) The repressor will no longer bind to the operator.
C) The operon will never be transcribed.
D) The genes of the lac operon will be transcribed continuously.

Question

Quizplus · Accepted Answer

Moving the operator past the transacetylase (lacA) gene would mean that the repressor protein would no longer be able to bind to the operator, allowing RNA polymerase to continuously transcribe the genes of the lac operon in the presence of lactose. Therefore, choice D is the best answer. Choice A is incorrect because the inducer (lactose) still needs to bind to the repressor to remove it from the operator, but this will no longer be necessary if the operator is moved. Choice B is also incorrect because the repressor will not be able to bind to the operator if it is moved. Choice C is also incorrect because the operon can still be transcribed if the operator is moved downstream of the genes.

Suppose an Experimenter Becomes Proficient with a Technique That Allows