The organic molecule tightly bound to the enzyme and required for the activity of enzyme is grouped as:

Options

A. apoenzyme
B. Co-enzyme
C. activator
D. prosthetic group

Answer

To answer the question regarding the organic molecule that is tightly bound to the enzyme and required for its activity, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Enzymes**: Enzymes are biological catalysts that speed up chemical reactions. They are composed of two main components: the apoenzyme and the coenzyme.

2. **Defining Apoenzyme**: The apoenzyme is the protein part of the enzyme. It is essential for the enzyme's structure but does not have catalytic activity on its own.

3. **Defining Coenzyme**: The coenzyme is a non-protein component that associates with the apoenzyme. It is necessary for the enzyme's catalytic activity but is not tightly bound to the enzyme.

4. **Understanding Prosthetic Groups**: The question specifies an organic molecule that is tightly bound to the enzyme. This characteristic aligns with what is known as a prosthetic group. A prosthetic group is a non-polypeptide unit that is tightly and permanently attached to a protein and is essential for its biological function.

5. **Examples of Prosthetic Groups**: Prosthetic groups can be organic (like vitamins, sugars, or lipids) or inorganic (like metal ions). They are crucial for the enzyme's activity and are tightly bound to the enzyme structure.

6. **Conclusion**: Based on the definitions and characteristics discussed, the correct answer to the question is that the organic molecule tightly bound to the enzyme and required for its activity is classified as a **prosthetic group**.