![]() The overall process of ATP generation via the harnessing of a proton motive force is called chemiosmosis. Proton motive force is the force created by the transfer of protons or electrons across a membrane that can be used for chemical, mechanical or osmotic. ![]() The following video discusses the above figure: The result is that protons quite strongly 'want' to cross the membrane from the right to the left, both to even out concentrations and to even out charges. In addition to the concentration gradient, there is a proton-associated positive charge to the right of the membrane and a proton- dearth-associated negative charge to the left. Since this is net movement, there is still movement that occurs going from left to the right (smaller, lighter arrow), just not as much. In the terminal step of oxidative- and photo-phosphorylation, it uses energy from a transmembrane, electrochemical gradient of protons (proton-motive force. This represents a concentration that can 'motivate' a net movement across the membrane – if that becomes possible – one going from the right to the left (large arrow). Proton concentrations are much greater to the right than they are to the left. One sees the tapping of proton motive forces particularly in both cellular respiration and photosynthesis, where they are used to generate ATP.įigure legend: The line in the middle represents a semipermeable membrane which does not permit movement of the protons ( H +) across, i.e., as equivalent to a lipid bilayer. ![]() A proton motive force is established via the action of either electron transport systems or instead membrane transport proteins that are known as proton pumps.Ī proton motive force can be tapped by protein complexes known as ATP synthases, which are reverse-running proton pumps that allow protons to cross membranes but in a manner that the drive of these protons to move from regions of high proton concentration to regions of low proton concentration (i.e., down their concentration gradient) captured to phosphorylate ADP, producing ATP.
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