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In E. coli, the lac operon gets switched...

In E. coli, the lac operon gets switched on when

A

lactose is present and it binds to the repressor

B

repressor binds to operator

C

RNA polymerase binds to the operator

D

lactose is present and it binds to RNA polymerase.

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The correct Answer is:
A
The repressor of the operon is synthesised (all the time constitutively) from the I gene .The repressor protein binds to the operator regions of the operon and prevents RNA polymerase from transcribing the operon, In th presence of an inducer, such as lactose or allolactose, the repressor is inactivated by interaction with the inducer.This allows RNA polymerase access to the promoter and transcription proceeds.Thus, the lac operon get switched on.
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