In operon concept, regulator gene functions as:

Options

A. Inhibitor
B. Repressor
C. Regulator
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding the Operon Concept**:
- The operon model is a genetic regulatory system found in bacteria. It consists of a cluster of genes that are transcribed together under the control of a single promoter.

2. **Components of an Operon**:
- An operon typically includes:
- **Regulator Gene**: Produces a protein that can bind to the operator.
- **Promoter**: The site where RNA polymerase binds to initiate transcription.
- **Operator**: A segment of DNA that the repressor protein can bind to, blocking RNA polymerase.
- **Structural Genes**: The genes that are co-regulated by the operon and are involved in a specific metabolic pathway.

3. **Function of the Regulator Gene**:
- The regulator gene produces a product (usually a protein) that can inhibit or repress the transcription of the structural genes. This product is often referred to as a repressor.

4. **Role of the Repressor**:
- The repressor binds to the operator region of the operon, preventing RNA polymerase from transcribing the structural genes. This effectively turns off the operon.

5. **Conclusion**:
- In the context of the operon concept, the regulator gene functions as an inhibitor, repressor, and regulator of gene expression. Therefore, the correct answer to the question is "all of these".

### Final Answer:
In the operon concept, the regulator gene functions as an inhibitor, repressor, and regulator, which means the answer is "all of these".

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