5. Which of the following statements about regulation of the lac operon is true?

ID: 80816 • Letter: 5

Question

5. Which of the following statements about regulation of the lac operon is true?

A. When glucose is present, gene expression is activated by lactose.

B. The amount of glucose in the growth medium does not affect the level of gene expression activated by lactose.

C. The binding of the Lac repressor to the operator is not affected by the presence of glucose.

D. Gene expression is high when the Lac repressor is not bound to the operator and glucose is available.

6. The ligand effector/inducer for the Lac repressor protein is:

A. lactose.

B. allolactose.

C. glucose.

D. ?-galactosidase.

7. The activator for the lac operon is:

A. CAP.

B. cAMP.

C. lactose.

D. allolactose.

8. The expression of the lac operon in an E. coli cell missing the gene that encodes for the lac repressor:

A. will increase when lactose is present.

B. will decrease when lactose is present.

C. will decrease when glucose is present.

5.Correct answer is:C. The binding of the Lac repressor to the operator is not affected by the presence of glucose

6.Correct answer is:B.allolactose

7.Correct answer is: B.cAMP

8.Correct answer is :C. will decrease when glucose is present.

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