Which of the following is NOT part of the endomembrane system?

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Multiple Choice

Which of the following is NOT part of the endomembrane system?

The endomembrane system is a coordinated network of membranes involved in making, sorting, and shipping proteins and lipids inside the cell. It includes the nuclear envelope (which is continuous with the endoplasmic reticulum), the endoplasmic reticulum itself, the Golgi apparatus, lysosomes, vesicles, and the plasma membrane. These compartments are physically connected by membrane traffic, so materials move from one to another through vesicles and connections. Mitochondria do not belong to this system. They have their own double membranes and distinct functions, primarily producing ATP through oxidative phosphorylation. They also contain their own DNA and ribosomes and import most of their proteins from the cytosol via specialized translocases, not by vesicular transport between endomembrane compartments. Because of this separation in structure and protein trafficking, mitochondria are not considered part of the endomembrane system.

The endomembrane system is a coordinated network of membranes involved in making, sorting, and shipping proteins and lipids inside the cell. It includes the nuclear envelope (which is continuous with the endoplasmic reticulum), the endoplasmic reticulum itself, the Golgi apparatus, lysosomes, vesicles, and the plasma membrane. These compartments are physically connected by membrane traffic, so materials move from one to another through vesicles and connections.

Mitochondria do not belong to this system. They have their own double membranes and distinct functions, primarily producing ATP through oxidative phosphorylation. They also contain their own DNA and ribosomes and import most of their proteins from the cytosol via specialized translocases, not by vesicular transport between endomembrane compartments. Because of this separation in structure and protein trafficking, mitochondria are not considered part of the endomembrane system.

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