Search results
Results from the WOW.Com Content Network
Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An important example is the formation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H + ) across a membrane during cellular respiration or photosynthesis .
A proton gradient is created across the thylakoid membrane (6) as protons (3) are transported from the chloroplast stroma (4) to the thylakoid lumen (5). Through chemiosmosis, ATP (9) is produced where ATP synthase (1) binds an inorganic phosphate group (8) to an ADP molecule (7).
This transport chain produces a proton-motive force, pumping H + ions across the membrane and producing a concentration gradient that can be used to power ATP synthase during chemiosmosis. This pathway is known as cyclic photophosphorylation, and it produces neither O 2 nor NADPH.
Oxidative phosphorylation is made up of two closely connected components: the electron transport chain and chemiosmosis. The electron transport chain in the cell is the site of oxidative phosphorylation. The NADH and succinate generated in the citric acid cycle are oxidized, releasing the energy of O 2 to power the ATP synthase.
In chemiosmosis, ions move down their electrochemical gradient across a membrane. Mitchell realised that the movement of ions across an electrochemical potential difference could provide the energy needed to produce ATP. His hypothesis was derived from information that was well known in the 1960s.
The chemiosmotic theory explained the mechanism for oxidative phosphorylation, stating that ATP synthesis requires chemiosmosis to function. [9] The proton gradient across the inner membrane of the mitochondria is created by the electron transport chain. This causes protons to re-enter the mitochondrial matrix through the protein ATP synthase.
This energy is used to synthesize ATP when the protons flow across the membrane (down their concentration gradient) through the ATP synthase complex; this is known as chemiosmosis. In endotherms, body heat is maintained by signaling the mitochondria to allow protons to run back along the gradient without producing ATP (proton leak).
Chemiosmosis. A major function of the thylakoid membrane and its integral photosystems is the establishment of chemiosmotic potential. The carriers in the electron ...