In E.coli during lactose metabolism, repressor binds to :

Options

A. Regulator gene
B. Operator gene
C. Structural gene
D. Promoter gene

Answer

To solve the question regarding where the repressor binds during lactose metabolism in E. coli, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the context of lactose metabolism in E. coli**:
- E. coli utilizes lactose as a source of energy. The metabolism of lactose is regulated by the lac operon.

2. **Identify the components of the lac operon**:
- The lac operon consists of several key components: the promoter (P), the operator (O), and structural genes (Z, Y, A). There is also a regulatory gene (I) that produces the repressor protein.

3. **Role of the repressor**:
- The repressor is a protein that is synthesized by the regulatory gene (I). Its primary function is to inhibit the transcription of the structural genes when lactose is not present.

4. **Binding site of the repressor**:
- The repressor binds specifically to the operator region (O) of the lac operon. When the repressor is bound to the operator, it prevents RNA polymerase from transcribing the structural genes (Z, Y, A), which are responsible for the metabolism of lactose.

5. **Conclusion**:
- Therefore, during lactose metabolism in E. coli, the repressor binds to the operator (O) region of the lac operon.

### Final Answer:
The repressor binds to the operator (O) in E. coli during lactose metabolism.

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