A non-protein organic part attached firmly by covalent linkage to apoenzyme is

Options

A. Cofactor
B. Coenzymes
C. Prosthetic group
D. Activator.

Answer

To solve the question, "A non-protein organic part attached firmly by covalent linkage to apoenzyme is," we can follow these steps:

### Step 1: Understand the Components of an Enzyme
An enzyme is a biological catalyst that speeds up chemical reactions. It is made up of two main components:
- **Apoenzyme**: The protein part of the enzyme.
- **Cofactor**: A non-protein component that assists in the enzyme's activity.

**Hint**: Remember that enzymes consist of both a protein part and a non-protein part.

### Step 2: Identify the Types of Cofactors
Cofactors can be further classified into:
- **Coenzymes**: Organic molecules that are loosely bound to the apoenzyme.
- **Prosthetic groups**: Non-protein organic molecules that are tightly bound to the apoenzyme via covalent bonds.

**Hint**: Distinguish between coenzymes and prosthetic groups based on their binding strength to the apoenzyme.

### Step 3: Analyze the Question
The question specifically asks for a "non-protein organic part" that is "attached firmly by covalent linkage" to the apoenzyme. This implies that we are looking for a component that is not a protein and is tightly bound.

**Hint**: Focus on the terms "non-protein" and "firmly attached by covalent linkage."

### Step 4: Evaluate the Options
Given the definitions:
- **Cofactor**: This term includes both coenzymes and prosthetic groups, but it does not specify the type of attachment.
- **Coenzyme**: These are loosely attached, so this option is incorrect.
- **Prosthetic group**: This is a non-protein organic part that is firmly attached by covalent linkage, making it a suitable answer.
- **Activator**: This is not a structural part of the enzyme but rather a separate entity that can modulate enzyme activity, so this option is incorrect.

**Hint**: Eliminate options based on their definitions and the specific requirements of the question.

### Step 5: Conclusion
The correct answer is **prosthetic group**, as it is the non-protein organic part that is firmly attached to the apoenzyme by covalent linkage.

**Final Answer**: Prosthetic group