Final answer:
The proton gradient in mitochondria drives the movement of hydrogen ions across the mitochondrial membrane and the synthesis of ATP through the process of chemiosmosis and ATP synthase.
Step-by-step explanation:
Processes driven by the proton gradient in mitochondria include the movement of hydrogen ions across a mitochondrial membrane and can also power cellular work directly. A well-known example is the bacterial flagellum, which is driven by proton flow through a cell membrane proton gate/molecular motor complex. Additionally, chemiosmosis, which involves the Electron Transport Chain (ETC), pumps protons (H+) across the mitochondrial membrane, establishing a proton gradient.
This proton gradient, also known as the proton motive force (PMF), is a form of stored free energy. When protons flow back into the mitochondrial matrix through ATP synthase complexes, they release this free energy, which is then harnessed as chemical energy for ATP synthesis. In summary, the proton gradient drives the movement of hydrogen ions across the mitochondrial membrane, facilitating ATP production.