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The generation of ATP by chemiosmosis occurs in mitochondria and chloroplasts, as well as in most bacteria and archaea. For instance, in chloroplasts during photosynthesis, an electron transport chain pumps H + ions (protons) in the stroma (fluid) through the thylakoid membrane to the thylakoid spaces
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.
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.
Two families of reaction centers in photosystems can be distinguished: type I reaction centers (such as photosystem I in chloroplasts and in green-sulfur bacteria) and type II reaction centers (such as photosystem II in chloroplasts and in non-sulfur purple bacteria). The two photosystems originated from a common ancestor, but have since ...
In bacteria and ATP-producing organelles other than mitochondria, reducing equivalents provided by electron transfer or photosynthesis power the translocation of protons. [citation needed] CF 1 ATP ligase of chloroplasts correspond to the human F O F 1 ATP synthase in plants. [citation needed]
The electron transport chain of green sulfur bacteria—such as is present in the model organism Chlorobaculum tepidum—uses the reaction center bacteriochlorophyll pair, P840. When light is absorbed by the reaction center, P840 enters an excited state with a large negative reduction potential, and so readily donates the electron to ...
In biology, electrochemical gradients allow cells to control the direction ions move across membranes. In mitochondria and chloroplasts, proton gradients generate a chemiosmotic potential used to synthesize ATP, [1] and the sodium-potassium gradient helps neural synapses quickly transmit information. [citation needed]