The transcription of beta galactosidase is regulated by the lac operon. The regulatory gene Lacl generates a repressor protein which regulates the initiation of transcription of the lac operon. The Lacl gene’s primary function is to suppress mRNA production for proteins encoded by the lac operon. It significantly reduces the levels of lacZYA mRNA transcription but does not completely stop transcription. This inhibition occurs due to Lacl’s specific binding to the lac operator (LacO) DNA sequence (and overlaps with the promoter). Thus, this creates competition between LacI and RNA polymerase for the region. LacI may also hinder transcription and/or prevent elongation of mRNA. When the cell lacks lactose, LacI binds to LacO, suppressing the transcription of genes in the lac operon. When lactose is present, enzymes allow for small amounts of sugar to enter bacteria via Lac Y. Lac Z subsequently breaks down lactose into glucose and galactose, providing energy and producing allolactose. Allolactose plays a key role in the process by binding to the lacZ repressor, and forms a positive feedback loop which modulates the cellular levels of beta galactosidase. Allolactose is the inducer for the lac operon.