Final answer:
The false statement about the Lac operon is that the Lac repressor binds when lactose is present in the cell. In reality, the Lac repressor binds when lactose is absent, preventing transcription of the structural genes. The presence of lactose and low glucose levels are necessary for the Lac operon to be transcribed.
Step-by-step explanation:
The false statement about the Lac operon is statement (a) The Lac repressor binds when lactose is present in the cell.
The Lac repressor actually binds to the operator region of the Lac operon when lactose is absent, preventing transcription of the structural genes. When lactose is present, it is converted to allolactose which acts as an inducer and binds to the repressor, preventing it from binding to the operator and allowing transcription to occur.
On the other hand, when glucose levels are low, cAMP binds to the CAP activator protein, allowing it to bind to DNA and activate transcription of the Lac operon. This addresses statement (b), showing that even when the CAP activator is bound to DNA, the Lac operon will only be transcribed when lactose is also present.
Regarding statement (c), the CAP activator can bind to DNA when cAMP is bound to it. High levels of glucose in the cell result in low cAMP levels, reducing the binding of CAP to DNA and therefore reducing the transcription of the Lac operon.