When both CAP and the lac repressor are bound as shown in the figure below, what happens to the genes in the lac operon?Group of answer choicesThe genes are transcribed once, but after that the repressor protein displaces the activatorThe genes are transcribed at a high level, because the activator will block the activity of the repressorThe genes are transcribed at a very low level, because when the repressor is bound to DNA it blocks RNA polymerase.The genes are transcribed half of the time, because the activator and repressor will each "win" half of the time

In E. coli, transcription of the lac operon would be increased by:Group of answer choicesA missense mutation that disrupts the activity of the catabolite activator protein (CAP).A mutation in the lacI repressor gene that increases the affinity of the repressor for allolactose.A mutation in the lacI repressor gene that increases the affinity of the repressor for the lac operator.The presence of glucose in the growth medium.

If E. coli bacteria are grown in the absence of lactoseMultiple Choicethe repressor will not bind the operator, thus allowing transcription of the lac operon genes.the repressor will bind the operator, thus allowing transcription of the lac operon genes.the repressor will not bind the operator, thus preventing transcription of the lac operon genes.the repressor will bind the operator, thus preventing transcription of the lac operon genes.No answer is correct.

When RNA polymerase is bound to the lac promoter sequence, transcription of the lac operon is on.

How does the lac repressor inhibit transcription?

The lac operon system, first described by Jacob and Monod, regulates lactose metabolism in . The is composed of a gene encoding a protein that normally keeps this operon in the position. Within the , the repressor binds to the , blocking transcription of structural genes needed for lactose metabolism. When is added to a cell's environment, it binds the repressor freeing the operator segment of the DNA. is now able to bind to the promoter, transcribing all three structural genes needed for lactose catabolism. When lactose again becomes depleted in the cell, the repressor binds to the operator blocking additional synthesis of enzymes from the .