question_answer

Gene regulation governing lactose operon of E. coli that involves the lac I gene products is

A)                          positive and inducible because it can be induced by lactose

B)  negative and inducible because repress or protein prevents transcription

C)  negative and repressive because repress or protein prevents transcription

D)  feedback inhibition because excess of \[\beta \]-galactosidase can switch off transcription

Correct Answer: B

Solution :

Lac I gene produces an inhibitor or rerpressor and negative regulation of lac operon, is induced. The repressor binds to the operator gene and stops its working. Repressor is meant to block the operator gene so that structural genes are unable to form -mRNA thus stopping the transcription of genes.