Question

1. Low levels of glucose:

Have no affect on cAMP levels

Increase levels of cAMP

decrease levels of cAMP

2.

The repressor contains:

A lactose binding site

A cAMP binding site

A glucose binding site

An RNA binding site

Answer 1

Ans1 : Low levels of glucose : Increase levels of cAMP ( When the intracellular level of glucose is low, a signal arises which is cAMP molecule, that acts as a signal for requirement of glucose in the cell & hence cAMP level in the cell rises due to low availablity of glucose. As the cAMP signal arises, it binds with CAP present  on the lac operon forming cAMP - CAP complex , that binds the DNA at a location upstream to lac - operon & increases the binding affinities & association of RNA polymerase & DNA. As a result, the transcription & translation occurs, leading to formation of proteins that later metabolizes the lactose into glucose , increasing glucose concentration in cell.

Ans 2 : The repressor contains : a lactose - binding site ( The repressor molecule regulates the on & off mechanism of lac - operon. It has two binding sites - for operator & for lactose).

* in presence of lactose : repressor binds with lactose, the operator is free to bind with RNA polymerase, initiating the transcription & translation (switch - on situation).

* in absence of lactose : repressor binds with operator region, preventing binding of RNA polymerase with operator , inhibiting the transcription & translation.( switch- off situation).

Hope this will help you?