Please give me the answer to the A-level Biology Question Describe how the lac operon works when lactose is both present and absent.
A-level Biology Help >>>>> Define how the lac operon functions in the event that lactose is both present and not. If lactose isn't present, the lac operon turns off. This is because there is a repressor proteins which binds with operators region. This blocks RNA polymerase from binding the operon, thereby preventing transcription of the structural genes. But, when lactose present, it converts into allolactose that binds the protein repressor. This alters the form of the protein that represses it, which means it will no longer be able to attach to the operator's region and stop transcription. This allows RNA Polymerase to be able to bind and transscribe the 3 structural genes for beta-galactosidase the beta-galactosidase permease, and the beta-gal.
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