Question

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease gene, which of the following would be likely?A) Three structural genes will no longer be expressed.B) The operon will no longer be inducible.C) The cell will continue to metabolize but more slowly. D) RNA polymerase will no longer transcribe permease.E) Beta galactosidase will be produced.

Answer 1

The right answer is B.

The operator is the segment of DNA to which a chemical signal (a regulatory molecule) binds. It can be either a repressor signal or a transcription activating signal (DNA operator) or translation (RNA operator) of the genes of the operon.

In the case of loperon lactose, the operator is located downstream of the promoter so that it can regulate the trancription. In the case of this experiment, the promoter has been removed from the opterator, and in this case, can no longer regulate the transcription, and therefore the synthesis will be continuous (unregulated).

Another interesting fact is that beta galactosidase will not be transcribed since it will be positioned upstream of the promoter (so the E response is false).