(CIE A2 Biology) Inheritance - gene control through the lac operon

the lac operon

an operon of DNA that contains three structural genes + operator and promoter regions

the lacZ gene

the structural gene of the lac operon that codes for beta-galactosidase (which hydrolyzes lactose molecules and catalyzes the binding of allolactose to the repressor protein)

the lacY gene

the structural gene of the lac operon that codes for lactose permease (which increases the permeability of plasma membranes to lactose)

the lacA gene

the structural gene of the lac operon that codes for transacetylase (which plays a role in lactose metabolism + detox)

the operator and promoter regions

the regions of the lac operon that switch structural genes on/off (the operator) and have RNA polymerase initiate transcription (the promoter) respectively

the lacI gene

codes for the lac operon’s repressor protein w/ its location slightly distant from the operon’s promoter

the lac operon’s repressor protein

an allosteric protein with two binding sites that makes allolactose’s binding to the lac operon’s operator impossible if it binds to the protein

when and how the lac operon’s structural genes are activated

in the presence of lactose where the repressor protein detaches itself from the operator allowing for RNA polymerase to bind to the promoter