Describe and explain how the lac Operon allows E coli bacteria to adapt to a new environment.

E. coli normally metabolise glucose, but if glucose is not available in a new environment, the lac operon can allow E. coli to metabolise lactose, the sugar found in milk using the structural genes beta-galactosidase and lactose permease. In the absence of lactose, the regulatory gene in the lac operon codes for a repressor protein, which binds to the operator region on the lac operon. This structurally blocks the promoter region of the lac operon so RNA polymerase cannot bind to the promoter region in order to transcribe the structural genes for beta-galactosidase and lactose permease. When lactose is present, it acts as an inducer molecule so it binds to the repressor protein forming the inducer-repressor complex, which can no longer bind to the operator region. This allows RNA polymerase to gain access to the promoter region in order to transcribe the structural genes which can then be translated into functional enzymes. Lactose permease transfers lactose into the cell, and beta-galactosidase hydrolyses lactose to glucose and galactose.