One of the major reasons for apoptosis is

Options

A. Lack of polymerases
B. Activity of endonucleases
C. Activity of mitochondria
D. Reduced food intake

Answer

**Step-by-Step Solution:**

1. **Understanding Apoptosis**: Apoptosis is defined as programmed cell death, which is a crucial process in multicellular organisms. It involves a series of cellular events that lead to characteristic morphological changes and ultimately cell death.

2. **Characteristics of Apoptosis**: During apoptosis, several changes occur in the cell, including:
- Cell blabbing (formation of bulges on the cell surface).
- Cell shrinkage.
- Nuclear fragmentation (breaking apart of the nucleus).
- DNA fragmentation (breaking apart of the DNA).
- RNA decay.

3. **Mechanism of Apoptosis**: The process of apoptosis is tightly regulated and can be initiated through various pathways. One of the major pathways is the intrinsic pathway, which is heavily reliant on the mitochondria.

4. **Role of Mitochondria**: Mitochondria are known as the powerhouse of the cell. They play a critical role in apoptosis by releasing proteins that increase the permeability of the mitochondrial membrane. This leads to the release of cytochrome C and other apoptotic factors.

5. **Caspases and Apoptotic Cascade**: The release of these proteins triggers a cascade of reactions involving caspases, which are enzymes that execute the cell death program. If mitochondria are damaged or destroyed, the cell cannot survive.

6. **Evaluating the Options**:
- **Lack of Polymerases**: Incorrect. Polymerases are involved in DNA and RNA synthesis, not directly in apoptosis.
- **Activity of Endonucleases**: Incorrect. Endonucleases cut DNA but do not directly lead to apoptosis.
- **Activity of Mitochondria**: Correct. Mitochondria play a crucial role in the intrinsic pathway of apoptosis.
- **Reduced Food Intake**: Incorrect. While prolonged starvation can affect cell survival, it does not directly induce apoptosis.

7. **Conclusion**: The major reason for apoptosis is the activity of mitochondria, making option C the correct answer.

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