The end prodict of metabolic panthway may bind a repressor to make the latter active enough to bind to operator. In this case the end-product is called :-

Options

A. Inducer
B. Aporepressor
C. Co-repressor
D. Regulator

Answer

To solve the question, we need to identify the term used to describe the end product of a metabolic pathway that binds to a repressor, making it active enough to bind to an operator. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding the Concept of Repressors**:
- Repressors are proteins that inhibit gene expression by binding to an operator and blocking RNA polymerase from transcribing the genes.

2. **Identifying the Role of End Products**:
- In metabolic pathways, the end products can regulate their own synthesis. When the concentration of an end product is high, it often binds to a repressor.

3. **Example of Tryptophan Operon**:
- The tryptophan operon (TRP operon) is a classic example where the end product, tryptophan, binds to the repressor protein. This binding activates the repressor.

4. **Mechanism of Action**:
- Once activated by tryptophan, the repressor can bind to the operator region of the operon, preventing transcription of the genes responsible for tryptophan synthesis.

5. **Conclusion**:
- Therefore, the end product in this context is referred to as a **co-repressor**. A co-repressor is a molecule that binds to a repressor and activates it, allowing it to bind to the operator and inhibit gene expression.

### Final Answer:
The end product is called a **co-repressor**.