Question

In the medium where E. coli was growing, lactose was added, which
induced the lac operon. Then, why does lac operon shut down some
time after addition of lactose in the medium?​

Answer 1

Answer:

In lac operon, lactose acts as an inducer. After sometime, when the level of inducer decreases as it is completely metabolized by enzymes, it causes synthesis of the repressor from regulator gene. The repressor binds to the operator gene and prevents RNA polymerase from transcribing the operon.