اپران لاکتوز
Lac Operon–
The Lac Operon is an inducible operon in Escherichia coli that controls the metabolism of lactose.

Components
•Regulatory gene (lacI): Produces the repressor protein.
•Promoter (P): Site where RNA polymerase binds.
•Operator (O): Acts as the on/off switch for transcription.

Structural genes:
•lacZ: Produces β-galactosidase (breaks lactose into glucose and galactose).
•lacY: Produces permease (helps lactose enter the cell).
•lacA: Produces transacetylase.

Working
•Without lactose: Repressor binds to the operator → RNA polymerase is blocked → Structural genes are not transcribed (Operon OFF).

•With lactose: Lactose is converted to allolactose (the inducer), which binds to the repressor → Repressor leaves the operator → RNA polymerase transcribes the structural genes → Enzymes for lactose metabolism are produced (Operon ON).
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