Question

For an electrophoretic mobility shift assay, you mix in a test tube bacterial cell extract and a 32P-labeled fragment of DNA that contains the CAP binding site and the lacP of the lac operon. It does not contain lacO or any of the structural genes. Which of the following would cause a mobility shift if added to the mix? Group of answer choices glucose lactose allolactose cAMP anti-lac repressor antibody anti-CAP antibody

a. glucose

b. lactose

c. allolactose

d. cAMP

e. anti-lac repressor antibody

f. anti-CAP antibody

Answer 1

Answer=(d)cAMP

Explanation-

CAP protein is activated by cAMP.The CAP dimer formed in the presence of cAMP so CAP dimer binds to the Promoter.Thus Protein-DNA interaction occurs which cause a mobility shift.

Now consider other option-

a)glucose-

Incorrect because in presence of glucose CAP protein can't bind at promoter.

b) Lactose-

Incorrect because it provides inducer.

c) Allolactose-

Incorrect because it is a inducer.

e)anti lac Repressor antibody-

Incorrect because Repressor can't activate CAP protein.

f)anti-CAP antibody-

Incorrect because for CAP protein activation cAMP needed.