Which of these is not part of the endomembrane system of the cell?

Options

A. Mitochondria
B. Endoplasmic reticulum
C. Lysosomes
D. Golgi complex

Explanation

To determine which of the given options is not part of the endomembrane system of the cell, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Endomembrane System**:
The endomembrane system consists of various membrane-bound organelles that work together to modify, package, and transport lipids and proteins. Key components include the endoplasmic reticulum, Golgi apparatus, lysosomes, nuclear envelope, vesicles, and the plasma membrane.

2. **Identify the Options**:
The options provided are:
- Mitochondria
- Endoplasmic reticulum
- Lysosomes
- Golgi apparatus

3. **Analyze Each Option**:
- **Endoplasmic Reticulum**: This organelle is part of the endomembrane system and is involved in the synthesis of proteins and lipids.
- **Lysosomes**: These are also part of the endomembrane system and are responsible for breaking down waste materials and cellular debris.
- **Golgi Apparatus**: This organelle is involved in modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles, making it part of the endomembrane system.
- **Mitochondria**: Unlike the others, mitochondria are not part of the endomembrane system. They are involved in cellular respiration and energy production but do not participate in the transport and sorting of molecules.

4. **Conclusion**:
Based on the analysis, the organelle that is not part of the endomembrane system is **Mitochondria**.

### Final Answer:
Mitochondria is not part of the endomembrane system of the cell.

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