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Multiple Choice
In the regulation of the lac operon, what is the role of cyclic AMP (cAMP)?
A
cAMP binds to the lac repressor, preventing it from binding to the operator.
B
cAMP binds to the CAP protein, enhancing transcription of the lac operon.
C
cAMP inhibits the synthesis of lactose, reducing the need for the lac operon.
D
cAMP directly binds to RNA polymerase, increasing its affinity for the promoter.
Verified step by step guidance
1
Understand the lac operon: The lac operon is a set of genes involved in lactose metabolism in E. coli. It is regulated by the presence or absence of lactose and glucose.
Identify the role of cAMP: Cyclic AMP (cAMP) is a signaling molecule that responds to glucose levels in the cell. When glucose is low, cAMP levels increase.
Explore the interaction between cAMP and CAP: cAMP binds to the catabolite activator protein (CAP), forming a cAMP-CAP complex.
Determine the effect of the cAMP-CAP complex: The cAMP-CAP complex binds to a specific site near the lac operon promoter, enhancing the binding of RNA polymerase and increasing transcription of the operon.
Conclude the role of cAMP: cAMP does not bind to the lac repressor or RNA polymerase directly. Its role is to enhance transcription by facilitating the binding of the cAMP-CAP complex to the promoter region, especially when glucose is scarce.