Final answer:
Bacteria can metabolize glucose without cyclic AMP (cAMP), but cAMP is essential for the activation of genes necessary for metabolizing alternative substrates when glucose is unavailable.
Step-by-step explanation:
The question at hand is whether bacteria require cyclic AMP (cAMP) for glucose metabolism. The correct answer is that cAMP is not needed for the initial metabolism of glucose, but it plays a crucial role when bacteria need to switch from glucose to other substrates like lactose. Specifically, in the presence of glucose, bacteria preferentially metabolize it without the need for cAMP. However, when glucose levels are low, bacteria produce less ATP, and Enzyme IIA (EIIA) becomes phosphorylated, leading to the activation of adenylyl cyclase, which increases cAMP levels in the cell. This increase in cAMP is important for the transcription of genes required for the metabolism of alternative substrates such as lactose, especially in Escherichia coli (E. coli). cAMP does this by binding to the catabolite activator protein (CAP), which then binds to regulatory regions to activate transcription. Therefore, while cAMP is not directly used in glycolysis - the pathway responsible for the initial breakdown of glucose - it is required in the regulatory processes that enable bacteria to use other substrates when glucose is scarce.
The lac Operon and Glucose Metabolism
Understanding the interaction between cAMP and the lac operon in bacteria such as E. coli is vital to comprehend cAMP's role in glucose metabolism. The lac operon is responsible for producing the enzymes that allow for lactose digestion when glucose is not present. When only lactose is available, cAMP levels increase, allowing CAP to activate the transcription of the lac operon. Thus, cAMP indirectly influences glucose metabolism by impacting bacteria's ability to process alternate sugars.