Question:
Regulation of lac operon is negative as:
Regulation of lac operon is negative as:
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Negative Control = Repressor turns it OFF.
Updated On: May 14, 2026
- operon is expressed at low level to allow lactose entry.
- lactose binds with the inducer to activate the operon.
- expression of operon is blocked by an active repressor.
- lactose needs a transporter to enter the cell.
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The Correct Option is C
Solution and Explanation
Step 1: Concept
Negative regulation refers to a system where the default state is "off" due to a repressor protein.
Step 2: Meaning
The lac repressor protein binds to the operator sequence to prevent transcription.
Step 3: Analysis
In the absence of lactose, the lac repressor is active and bound to the DNA, physically blocking RNA polymerase. Because an active repressor is required to shut down the operon, the regulation is termed negative.
Step 4: Conclusion
The inhibitory action of the repressor protein defines the negative control of the lac operon. Final Answer: (C)
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