1. Electron Transport Chain: Electrons are passed along a chain of proteins embedded in the inner mitochondrial membrane. This process releases energy, which is used to pump protons from the mitochondrial matrix to the intermembrane space.
2. Proton Gradient: The pumping action creates a proton gradient, with a higher concentration of protons in the intermembrane space than in the matrix. This gradient represents potential energy.
3. ATP Synthase: Protons flow down their concentration gradient, moving back across the inner mitochondrial membrane through a protein complex called ATP synthase. This flow of protons drives the rotation of a part of ATP synthase, which in turn catalyzes the phosphorylation of ADP to ATP.
Therefore, the movement of protons across the inner mitochondrial membrane is the key driving force for ATP synthesis during chemiosmosis.
