1. Electrons are passed down a chain: The electron transport chain is a series of protein complexes embedded in the inner mitochondrial membrane. Electrons, initially carried by NADH and FADH2, are passed from one complex to the next.
2. Energy is released: As electrons move down the chain, they lose energy. This energy is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space.
3. Proton gradient is established: This pumping creates a proton gradient across the inner mitochondrial membrane, with a higher concentration of protons in the intermembrane space.
4. Protons flow back: Protons naturally flow back into the matrix through a protein channel called ATP synthase.
5. ATP is synthesized: The flow of protons through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate (Pi).
In summary: The electron transport chain uses the energy released by electrons to pump protons, creating a proton gradient that powers ATP synthesis. This process is essential for cellular respiration and provides the majority of the ATP needed by cells.
