It's important to regulate genes so it does nothing unnecessarily. This will help it save energy. Different specialized cells and factors control the making of genes and the way they do it depends on its environment. The regulators can be turned on and off depending on why and how t needs and uses things around it. There are also necessary factors that allow gene regulation. E Coli must regulate the lac gene so it is used properly. If there is lactose around it, it must be switched on to process it. If there is no lactose around, then it must turn off to save energy because there is no reason for it to be in use.