Q 10. Gene regulation governing lactose operon of E.coli that involves the lac l gene product is
(1) Feedback inhibition because excess of galactosidase can switch off transcription
(2) Positive and inducible because it can be induced by lactose
(3) Negative and inducible because repressor protein prevents transcription
(4) Negative and repressible because repressor protein prevents transcription
Dear Student,
The correct answer is option (3) Negative and inducible because repressor protein prevents transcription.
Lactose operon consists of four genes LacZ, LacY, LacA and LacI. Genes Z, Y and A are structural genes whereas LacI gene encodes for a repressor that in the absence of an inducer ,i.e., allolactose binds to the promoter of Lac operon to inhibit the transcription of the structural genes.
When there is no inducer, LacI gene encodes repressor to inhibit the transcription. This type of regulation is known as a negative regulation.
Regards
The correct answer is option (3) Negative and inducible because repressor protein prevents transcription.
Lactose operon consists of four genes LacZ, LacY, LacA and LacI. Genes Z, Y and A are structural genes whereas LacI gene encodes for a repressor that in the absence of an inducer ,i.e., allolactose binds to the promoter of Lac operon to inhibit the transcription of the structural genes.
When there is no inducer, LacI gene encodes repressor to inhibit the transcription. This type of regulation is known as a negative regulation.
Regards