Final answer:
Catabolite activation is a positive control exerted by CAP in E. coli. It involves the binding of CAMP to CAP, which then binds to the promoter region of the genes required for processing alternative sugar sources. This increases RNA polymerase binding and promotes transcription of the genes.
Step-by-step explanation:
When glucose levels decline in E. coli, cyclic AMP (CAMP) accumulates in the cell and binds to the catabolite activator protein (CAP). CAP then forms a complex with the promoter region of the genes that are needed to use alternative sugar sources. This binding increases the binding ability of RNA polymerase to the promoter region and promotes transcription of the genes. This process is known as catabolite activation and it allows the bacteria to use alternative sugars for energy when glucose is scarce.