(Solved): 3. The lac-operon is a DNA sequence primarily responsible for regulating gene activity for proteins ...

3. The lac-operon is a DNA sequence primarily responsible for regulating gene activity for proteins involved in lactose transport in bacteria. It has also been heavily utilized in molecular genetics as a regulator of genes cloned into plasmids. These plasmids are transformed (put into) bacteria that are then fed lactose, which causes expression of the plasmid gene, and expression of a protein of interest. Gene expression in this system is therefore regulated by lactose (ligand) binding to a protein that will in turn bind DNA at the lac-operon and (eventually) recruit a polymerase for transcription. You don't need to investigate the complexity of the protein scaffold that results prior to the actual transcription event, let alone DNA transcription. I just want you to explain how, possibly, using any useful protein-ligand interaction model, the lac-operon is often observed to be "leaky" (active/productive) without feeding the bacteria lactose. (note: the real answer is more complex than anything you can come up with. All you need is class information).