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uestion With respect to transcription of the lac operon, O it is activated when the lac repressor releases the inducer molecule ® it is inactivated by CAP binding to the operator it is inactivated by cAMP's presence ( it requires RNA polymerase O all of the above are true LiC none of the above are truc

Answer 1

Ans is all of the above
Lactose is not the preferred carbohydrate source for E coli. If lactose and glucose are present, the cell will use all of the glucose before the lac operon is turned on. This type of control is termed catabolite repression. To prevent lactose metabolism, a second level of control of gene expression exists. The promoter of the lac operon has two binding sites. One site is the location where RNA polymerase binds. The second location is the binding site for a complex between the catabolite activator protein (CAP) and cyclic AMP (cAMP). The binding of the CAP CAMP complex to the promoter site is required for transcription of the lac operon. The presence of this complex is closely associated with the presence of glucose in the cell. As the concentration of glucose increases the amount of CAMP decreases. As the CAMP decreases, the amount of complex decreases. This decrease in the complex inactivates the promoter, and the lac operon is turned off. Because the CAP-CAMP complex is needed for transcription, the complex exerts a positive control over the expression of the lac operon.

The lac repressor protein binds to the operator and blocks RNA polymerase from binding to the promoter and transcribing the operon. The promoter is the binding site for RNA polymerase, the enzyme that performs transcription. The operator is a negative regulatory site bound by the lac repressor protein.