Which of the following is a co-factor and tightly bound to the apoenzyme?

Options

A. Coenzyme
B. Prosthetic group
C. Zymogens
D. Isoenzymes

Answer

To solve the question, "Which of the following is a co-factor and tightly bound to the apoenzyme?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Enzymes**:
- Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are primarily proteins.

2. **Identifying Components of Enzymes**:
- Enzymes consist of two main components:
- **Apoenzyme**: The protein part of the enzyme.
- **Cofactor**: A non-protein component that assists in enzyme activity.

3. **Types of Cofactors**:
- Cofactors can be further classified into two categories:
- **Coenzymes**: These are organic molecules that are loosely bound to the apoenzyme and often act as carriers for chemical groups.
- **Prosthetic Groups**: These are inorganic or organic molecules that are tightly bound to the apoenzyme and are essential for its activity.

4. **Identifying the Correct Answer**:
- The question specifically asks for a cofactor that is tightly bound to the apoenzyme. This definition matches the term "prosthetic group."
- Therefore, the correct answer is **Option B: Prosthetic Group**.

5. **Eliminating Incorrect Options**:
- **Coenzyme**: Incorrect because it is loosely bound.
- **Zymozyme**: Incorrect as it is not a recognized term in this context.
- **Isoenzyme**: Incorrect as it refers to different enzymes that catalyze the same reaction but differ in structure.

### Final Answer:
The correct answer is **Option B: Prosthetic Group**.

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