What will be the binding status of regulatory proteins in lac operon when concentrations of both lactose and glucose are very low in the culture medium?a)Only the repressor remains bound to the operatorb)Only the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex remains bound to the CAP binding sitec)Neither the repressor nor cAMP-CAP complex remain bound to their respective binding sitesd)Both the repressor and cAMP-CAP complex remain bound to their respective binding sitesCorrect answer is option 'B'. Can you explain this answer?

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What will be the binding status of regulatory proteins in lac operon when concentrations of both lactose and glucose are very low in the culture medium?

a)
Only the repressor remains bound to the operator
b)
Only the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex remains bound to the CAP binding site
c)
Neither the repressor nor cAMP-CAP complex remain bound to their respective binding sites
d)
Both the repressor and cAMP-CAP complex remain bound to their respective binding sites

Correct answer is option 'B'. Can you explain this answer?

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What will be the binding status of regulatory proteins in lac operon w...

Catabolite control of the lac operon. The operon is inducible by lactose to the maximal levels when CAMP and CAP form a complex. (a) Under conditions of high glucose, a glucose breakdown product inhibits the enzyme adenylate cyclase, preventing the conversion of ATP into CAMP. (b) Under conditions of low glucose, there is no breakdown product, and therefore adenylate cyclase is active and CAMP is formed. (c) When CAMP is present, it acts as anallosteric effector, complexing with CAP. (d) The CAMP–CAP complex acts as an activator of lac operon transcription by binding to a region within the lac promoter. (CAP = catabolite activator protein; cAMP = cyclic adenosine monophosphate.)

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What will be the binding status of regulatory proteins in lac operon w...

The lac operon is a regulatory system found in bacteria that controls the expression of genes involved in lactose metabolism. It consists of three key components: the lacZ, lacY, and lacA genes, the lac repressor protein, and the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex.

When lactose is present in the culture medium, it can be transported into the bacterial cell and converted into glucose and galactose by the lacZ and lacY genes. In the absence of lactose, the lac repressor protein binds to the operator region of the lac operon, preventing the transcription of the lac genes. However, when lactose is present, it binds to the lac repressor protein and induces a conformational change, causing the repressor to dissociate from the operator and allowing the lac genes to be transcribed.

On the other hand, glucose is a preferred carbon source for bacteria, and its presence in the culture medium can inhibit the expression of the lac operon. When glucose levels are high, the concentration of cyclic AMP (cAMP) inside the cell is low. The cAMP-CAP complex is required for efficient transcription of the lac operon, as it binds to a specific site upstream of the lac promoter and helps recruit RNA polymerase to initiate transcription.

When both lactose and glucose concentrations are very low in the culture medium, the binding status of regulatory proteins in the lac operon is as follows:

1. The repressor remains bound to the operator: The lac repressor protein binds to the operator region of the lac operon in the absence of lactose. Even though lactose concentrations are low, the repressor remains bound to the operator, preventing the transcription of the lac genes.

2. The cAMP-CAP complex does not remain bound to the CAP binding site: When glucose concentrations are low, the concentration of cAMP inside the cell is high. This high cAMP level allows the cAMP-CAP complex to bind to the CAP binding site upstream of the lac promoter. However, when glucose levels are very low, the concentration of cAMP decreases, and the cAMP-CAP complex dissociates from the CAP binding site. As a result, the recruitment of RNA polymerase to the lac promoter is reduced, leading to decreased transcription of the lac genes.

Therefore, in this scenario, only the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex remains bound to the CAP binding site, while the repressor remains bound to the operator.

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What will be the binding status of regulatory proteins in lac operon when concentrations of both lactose and glucose are very low in the culture medium?a)Only the repressor remains bound to the operatorb)Only the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex remains bound to the CAP binding sitec)Neither the repressor nor cAMP-CAP complex remain bound to their respective binding sitesd)Both the repressor and cAMP-CAP complex remain bound to their respective binding sitesCorrect answer is option 'B'. Can you explain this answer?

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