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BIO 120 Chapter 13

The lac operon is expressed when
A) glucose is high and lactose is absent.
B) glucose is low and lactose is absent.
C) glucose is low, regardless of the presence or absence of lactose.
D) glucose is high and lactose is present.
E) glucose is low and lactose is present.
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The lac operon is expressed when
A) glucose is high and lactose is absent.
B) glucose is low and lactose is absent.
C) glucose is low, regardless of the presence or absence of lactose.
D) glucose is high and lactose is present.
E) glucose is low and lactose is present.
E
When in a complex with ________, the CAP protein binds to the CAP site and ________ the expression of the lac operon.
A) glucose ; switches on
B) lactose ; switches on
C) cAMP ; switches on
D) cAMP ; switches off
E) glucose ; switches off
C
In the absence of lactose, the lac repressor is
A) active and can bind to the operator.
B) inactive and can bind to the operator.
C) active and cannot bind to the operator.
D) inactive and cannot bind to the operator.
E) inactive and cannot bind to the promoter.
A
Which region associated with the lac operon is not involved in the binding of RNA polymerase?
A) lacO
B) lacZ Correct
C) CAP binding site
B
How does glucose effect the lac operon?
A) When glucose levels are high, glucose binds to and deactivates the repressor, preventing it from binding to the DNA.
B) When glucose levels are low, it stimulates the production of cAMP, which binds to and deactivates the repressor, preventing it from binding to the DNA.
C) When glucose levels are low, glucose binds to and activates the repressor, causing it to associate with the DNA.
D) When glucose levels are high, it stimulates the production of cAMP, which binds to and deactivates the CAP protein, preventing it from binding to the DNA.
E) When glucose levels are low, it stimulates the production of cAMP, which binds to and activates the CAP protein, allowing it to bind to the DNA.
NOT A B C E
NOT A B D