The lac operon is a negatively controlled inducible operon, where the inducer molecule is Lactose. If the inducer molecule is present, it binds to the repressor and changes its conformation so that it is unable to bind to the operator and thus gene expression is controlled.

Is a negative inducible operon is normally on?

When are negative repressible operons turned off? Operons are normally on producing product needed by the cell, however it is turned off when there are adequate amounts of the product already present.

What is negative control of lac operon?

The lac operon exhibits both systems. It is a negative control system because expression is typically blocked by an active repressor (the lac repressor) that turns off transcription. The lac repressor binds to the operator region and negatively controls (prevents) transcription.