Question

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences wil prokaryotic genome.If she moves the promoter for the lac operon to the region between the beta galactosidase (lacz) gene and the permease (lacy) gene, which of the following would be likely? A) RNA polymerase will no longer transcribe permease. B) The cell will continue to metabolize but more slowly. C) The operon will no longer be inducible. D) Beta galactosidase will not be produced. E) The three genes will be expressed normally.

Answer 1

Answer:

D) Beta galactosidase will not be produced.

Explanation:

Promoter is necessary to start the transcription of the structural gene. The position of promoter is important because the gene which is downstream to promoter will be transcribed and the gene upstream to the promoter will not be transcribed.

Lac operon has three structural gene lacZ, lacY, and lacA. Lac Z codes for β galactosidase, lac Z codes for permease and Lac A codes for transacetylase. So if promoter for the lac operon moves between the beta-galactosidase (lacz) gene and the permease (lacy) gene, then the beta-galactosidase gene will not be produced because it is places upstreamed to the promoter.