Question

The Electron Transport Chain creates potential energy by pushing protons to one side of the membrane, increasing the concentration on that side. What eventually happens to that energy? Explain in detail.

Answer 1

Transfer of electrons through the electron transpot chain is accompanied by pumping of protons across inner mitochrondrial membrane, from the mitochrondrial matrix to inner membrane space.A total of 10H+ ions are translocated from the matrix across the inner mitochrondrial membrane per electron pair flowing from NADH to O2.   This movement of H+ generates: pH gradient and voltage gradient.

This creates an action of electrchemical gradient for protons , with lower pH value outside the inner mitochrondrial membrane than inside. The proton on the outside have a thermodynamic tendency of flow back in to the matrix so as to equalize pH. When protons do flow back into the matrix ,the energy is dissipated, some of it being used to drive the synthesis of ATP.T his mechanism is well explained in the chemiosmotic theory proposed by the Peter Mitchell in 1961.