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.
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.
This reflux releases free energy produced during the generation of the oxidized forms of the electron carriers (NAD + and Q) with energy provided by O 2. The free energy is used to drive ATP synthesis, catalyzed by the F 1 component of the complex. [13] Coupling with oxidative phosphorylation is a key step for ATP production.
In cyclic photophosphorylation, cytochrome b 6 f uses electrons and energy from PSI to create more ATP and to stop the production of NADPH. Cyclic phosphorylation is important to create ATP and maintain NADPH in the right proportion for the light-independent reactions. The net-reaction of all light-dependent reactions in oxygenic photosynthesis ...
ATP synthase is an enzyme that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (P i). ATP synthase is a molecular machine. The overall reaction catalyzed by ATP synthase is: ADP + P i + 2H + out ⇌ ATP + H 2 O + 2H + in
The energy required for the proton pumping reaction may come from light (light energy; bacteriorhodopsins), electron transfer (electrical energy; electron transport complexes I, III and IV) or energy-rich metabolites (chemical energy) such as pyrophosphate (PPi; proton-pumping pyrophosphatase) or adenosine triphosphate (ATP; proton ATPases).
By replenishing lost electrons with electrons from the splitting of water, photosystem II provides the electrons for all of photosynthesis to occur. The hydrogen ions (protons) generated by the oxidation of water help to create a proton gradient that is used by ATP synthase to generate ATP .