A coenzyme is

Options

A. Organic non-proteinaceous group that is essential for enzyme activity
B. Organic or inorganic group that is essential for enzyme activity
C. Same enzyme found in different organs or tissues
D. One that shares function of another enzyme.

Answer

**Step-by-Step Solution:**

1. **Understanding Coenzymes**: A coenzyme is a type of cofactor that is essential for the activity of certain enzymes. It is important to note that coenzymes are not proteins themselves.

2. **Identifying the Nature of Coenzymes**: Coenzymes are organic molecules. This differentiates them from other types of cofactors, which can be inorganic (like metal ions).

3. **Role of Coenzymes**: Coenzymes assist enzymes in catalyzing reactions. They may bind loosely or tightly to the enzyme. When they bind loosely, they are referred to as coenzymes, while if they bind tightly, they are called prosthetic groups.

4. **Conclusion**: Based on the definitions and roles discussed, we can conclude that a coenzyme is an organic, non-proteinaceous group that is essential for enzyme activity.

5. **Final Answer**: Therefore, the correct answer is: "A coenzyme is an organic non-proteinaceous group that is essential for enzyme activity."

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