Lac operon mol biology

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The lac operon consists of three structural genes: lacZ, lacY, and lacA. • lacZ encodes β-galactosidase, which breaks down lactose into glucose and galactose. • lacY encodes lactose permease, a membrane protein that transports lactose into the cell. • lacA encodes β-galactoside transacetylase, an enzyme of unknown physiological role in E. coli. • The operon also contains a promoter, an operator, and the regulatory gene lacI • The lac operon is negatively regulated by the lac repressor protein encoded by lacI. • In the absence of lactose, the lac repressor binds to the operator sequence, preventing transcription of the structural genes • When lactose is present, it is converted to allolactose, which binds to the lac repressor, causing a conformational change that prevents the repressor from binding to the operator. • Transcription is also activated by the catabolite activator protein (CAP) when glucose levels are low, allowing the lac operon to be expressed only when lactose is present and glucose . • #biologylectures • #neetncertbiology • #neet 2025 • #molecularbasisofinheritanceclass12 • #biology • #biologysimplified • #molecularbasisofinheritance • #science

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