The inducer of Lac operon binds to

Options

A. Repressor gene
B. Repressor protein
C. Operator gene
D. Promoter gene

Answer

To solve the question regarding the inducer of the Lac operon, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Lac Operon**: The Lac operon is a set of genes in E. coli that are involved in the metabolism of lactose. It consists of structural genes (lacZ, lacY, and lacA), a promoter, an operator, and a repressor.

2. **Identify the Inducer**: The inducer of the Lac operon is allolactose, which is derived from lactose. When lactose is present in the environment, some of it is converted into allolactose.

3. **Mechanism of Induction**: Allolactose binds to the repressor protein. The binding of allolactose to the repressor causes a conformational change in the repressor, reducing its affinity for the operator region of the operon.

4. **Effect of Inducer Binding**: When the repressor is bound to allolactose, it cannot bind to the operator. This allows RNA polymerase to access the promoter and initiate transcription of the structural genes.

5. **Evaluate the Options**:
- **Repressor Gene**: This is not correct; the inducer does not bind to the gene itself.
- **Repressor Protein**: This is correct; the inducer binds to the repressor protein.
- **Operator Gene**: This is incorrect; the inducer does not bind here.
- **Promoter Gene**: This is also incorrect; the inducer does not bind to the promoter.

6. **Conclusion**: The correct answer is that the inducer of the Lac operon binds to the repressor protein.

### Final Answer:
The inducer of the Lac operon binds to the repressor protein.

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