For some time it was not clear whether lac repressor inhibits lac operon transcription by inhibiting the binding of RNA polymerase to its promoter or by allowing transcription initiation but blocking elongation past the site of bound repressor.
How might you distinguish between these possibilities? Fill in the blanks with the options given to complete the following sentences.

in one gel, in separate gels, Northern blot, repressor, Western blot, inducer

Incubate a plasmid containing the lac operon with lac . Then add RNA polymerase and Northern blot analyze the mixture by gel electrophoresis and probe the gel with antibodies to RNA polymerase and repressor .

Incubate a plasmid containing the lac operon with lac __REPRESSOR. Then add RNA polymerase and Northern blot analyze the mixture by gel electrophoresis and probe the gel _WESTERN BLOT with antibodies to RNA polymerase and repressor _IN SEPERATE GELS.

Explanation:

Incubate a plasmid containing the lac operon with lac __REPRESSOR. Then add RNA polymerase and Northern blot analyze the mixture by gel electrophoresis and probe the gel _WESTERN BLOT with antibodies to RNA polymerase and repressor _IN SEPERATE GELS.

they both go up but then go back down. they both end lower than they started. lastly, they both are competitive/the second on.

explanation:

i believe it would cause an increase of percipitation, though i could be wrong. so i would say b is the answer.