Intermembrane space

Intermembrane space is a term used in cell biology to refer to the space occurring between the inner and outer membranes of a cell's mitochondria or chloroplasts. This space plays a crucial role in the energy production processes of the cell, particularly in the electron transport chain and chemiosmosis.

Structure and Composition

The intermembrane space is similar in composition to the cytosol of the cell, as it is in direct contact with it at places where the outer mitochondrial membrane is permeable. It contains a high concentration of proteins and other molecules that are involved in the process of oxidative phosphorylation.

Function

The primary function of the intermembrane space is to serve as a site for the transfer of electrons and protons during the process of oxidative phosphorylation. This process is part of the larger metabolic pathway known as cellular respiration, which is responsible for the production of adenosine triphosphate (ATP), the cell's main source of energy.

During the electron transport chain, electrons are passed along a series of proteins embedded in the inner mitochondrial membrane. As these electrons move, they cause protons to be pumped from the mitochondrial matrix into the intermembrane space. This creates a proton gradient, which is used to drive the synthesis of ATP during chemiosmosis.

Role in Apoptosis

The intermembrane space also plays a role in the process of apoptosis, or programmed cell death. Certain proteins that are involved in the initiation of apoptosis, such as cytochrome c, are stored in the intermembrane space. When a cell receives a signal to undergo apoptosis, these proteins are released from the intermembrane space into the cytosol, where they trigger the cascade of events that leads to cell death.

See Also

• Mitochondria
• Chloroplast
• Cellular respiration
• Apoptosis

References

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  Animal mitochondrion diagram

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  Electron transport chain

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  Reactions of peroxynitrite leading to either apoptotic or necrotic cell death

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  Chloroplast

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  Diagram of human cell nucleus