1. lacZ lacY lacA OA i Repressor lactose lactose/repressor RNA pol CRP cAMP CRP/cAMP complex CAP complex B-galactosidase lactose permease transcetylase operator activatorRegulatory gene P lacZ lacY lacA OA i NO transcription lacZ lacY lacA OA i NO transcription lacZ lacY lacA OA i Transcription occurs lacZ lacY lacA OA i Lac operon

2. lacZ lacY lacA OA i Repressor lactose lactose/repressor RNA pol CRP cAMP CRP/cAMP complex CAP complex B-galactosidase lactose permease transcetylase operator activatorRegulatory gene P lacZ lacY lacA OA i NO transcription lacZ lacY lacA OA i NO transcription lacZ lacY lacA OA i Transcription occurs lacZ lacY lacA OA i

3. Repressor lactose RNA pol (CRP)CAP cAMP lacZ lacY lacA OA i Regulatory gene P lacZ lacY lacA OA i OA i

4. Not taken up Lots of glucose Repressor lactose lactose/repressor RNA pol CRP cAMP CRP/cAMP complex CAP complex IIC glycolysis Glucose PEP Pyruvate Kreb’s IIB HPr IIA EI ATP glucose lactose Low cAMP

5. Repressor lactose lactose/repressor RNA pol CRP cAMP CRP/cAMP complex CAP complex IIC glycolysis Glucose PEP Pyruvate Kreb’s HPr IIA EI ATP IIB lactose Adenylate cyclase Not more glucose This process slows down Levels of cAMP increase

6. Repressor lactose lactose/repressor RNA pol CRP cAMP CRP/cAMP complex CAP complex IIC glycolysis Glucose PEP Pyruvate Kreb’s HPr IIA EI ATP IIB lactose Adenylate cyclase Not more glucose This process slows down lacOp becomes active