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What is the lac operon, and how is it regulated?
Original Khojo Papers practice question — not from a past board paper.
Answer
The lac operon of Escherichia coli consists of a promoter, an operator and three structural genes, z, y and a, that make the enzymes for lactose metabolism. In the absence of lactose a repressor protein binds the operator and blocks transcription. When lactose is present it acts as an inducer, binds the repressor and inactivates it, so RNA polymerase can transcribe the genes.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
It is an example of negative regulation of an inducible operon.
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