Top: The operator is shown in red, part of the DNA. It is bound to the repressor (green), which prevents RNA polymerase (yellow) from transcribing the target genes (6,7,8). Bottom: The green repressor is inhibited by the white molecule. RNA polymerase (yellow) is free to transcribe the target genes (6,7,8). This particular process shows the operator's role in the lac operon. Lactose is the white molecule in the bottom diagram.