Energy Capture During Electron Transport

Energy Capture During Electron Transport 

As electrons pass through complexes I, III, and IV (but not complex II), protons are transported across the inner mitochondrial membrane from the matrix to the intermembrane space, creating a pH gradient that represents a form of stored energy. 

The pH gradient is used to drive ATP synthesis by the movement of protons back to the matrix through a transmembrane protein complex, or ATP synthase. 

This mechanism was first described as the chemiosmotic theory of ATP generation, or the Mitchell hypothesis. 

As protons pass through a channel in the ATP synthase complex, ADP and P, are joined to form ATP. 

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VIII. Energy Capture During Electron Transport... 

Most of the aerobic cell s free energy is captured by the mitochondrial electron transport system (Chapter 10). During this process, electrons are transferred from a redox pair with a more negative reduction potential (NADH/NAD+) to those with more positive reduction potentials. The last component in the system is the H20/ /2 02 pair ... 

The chemical energy liberated during oxidation of the Krebs cycle substrates is captured in the electron transport chain and delivered in small packages to yield the energy-rich phosphate bond of ATP. 

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