Question

What conditions must be present for transcription of the Lac Operon genes? What is the function of a repressor protein if lactose is absent?

Answer 1

Lactose must bond to the repressor.

Explanation:

The repressor blocks the transcription of the lac genes when lactose isn't bonded to it, but is inhibited when lactose is bonded to it (meaning the repressor no longer blocks transcription).

Here's a picture: (2 is the repressor and 5 is the lactose)