Question:
The repressor protein in lac operon is produced by the action of ________.
The repressor protein in lac operon is produced by the action of ________.
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The regulator (i) gene codes for the repressor protein.
Updated On: Nov 12, 2026
- operator gene
- regulator gene
- promoter gene
- structural gene
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept
The lac operon contains a regulator gene, a promoter, an operator and the structural genes z, y and a.
Step 2: Identify the gene
The regulator gene is expressed on its own and codes for the repressor protein.
The repressor binds the operator and blocks RNA polymerase until lactose acts as an inducer.
Step 3: Why the other options fail
The operator and promoter are only binding sites, and the structural genes code for enzymes that use lactose.
Final Answer:
The repressor is produced by the regulator gene. \[ \boxed{\text{(B) }\text{regulator gene}} \]
The lac operon contains a regulator gene, a promoter, an operator and the structural genes z, y and a.
Step 2: Identify the gene
The regulator gene is expressed on its own and codes for the repressor protein.
The repressor binds the operator and blocks RNA polymerase until lactose acts as an inducer.
Step 3: Why the other options fail
The operator and promoter are only binding sites, and the structural genes code for enzymes that use lactose.
Final Answer:
The repressor is produced by the regulator gene. \[ \boxed{\text{(B) }\text{regulator gene}} \]
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