Mitochondrial Inner Membrane: Definition & Overview

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  • 0:00 Definition
  • 1:13 Processes
  • 1:29 The Electron Transport Chain
  • 2:44 Lesson Summary
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Lesson Transcript
Instructor: Nicholas Gauthier
The inner membrane of the mitochondrion is involved in the final step in aerobic respiration. Discover the intricacies of this membrane and how it is the key to unlocking the full energy potential of food.


The mitochondria is known as the powerhouse of the cell and exists in all eukaryotic cells, able to extract a significant amount of energy from each glucose molecule. The mitochondrion has an outer membrane and an inner membrane. The mitochondrial inner membrane is the site of the electron transport chain, an important step in aerobic respiration. Between the inner membrane and outer membrane is the inter-membrane space. There, H+ ions build up to create a proton potential that helps power the ATP energy formation. ATP is the energy currency of the cell. It is a relatively simple molecule that cells use to power their life processes. It is created with the help of ATP synthase, an enzyme embedded in the inner mitochondrial membrane.

The mitochondrial inner membrane is made primarily of a phospholipid bilayer, just like the cell membrane. Embedded in this bilayer are various proteins that serve to carry out the electron transport chain. The membrane has folds called christae that increase its surface area.


The citric acid cycle takes the products of glycolysis, an anaerobic process, and creates several NADH and FADH2 molecules. These molecules then enter the the electron transport chain, where they contribute their energy to the creation of ATP.

The Electron Transport Chain

The products of the citric acid cycle are sent to the electron transport chain. These products are NADH and FADH2. They contribute electrons to the electron transport chain, where they create a negative current along the inner membrane. This negative current attracts H+ ions across the inner membrane. Recall that H+ ions are simply protons all by themselves.

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