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Animation: Electron Transport

by Pearson
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Most of the energy harvested from organic molecules during glycolysis and the citric acid cycle is stored in NADH and FADH2. These molecules give up their high-energy electrons in the third phase of cellular respiration, oxidative phosphorylation, where most of the cell's ATP fuel is produced. The electron transport chain is an array of molecules, mostly proteins, built into the inner membrane of the mitochondrion. NADH gives up its high-energy electrons to the first complex in the electron transport chain. The electrons move from one member of the chain to the next, giving up their energy as they are pulled from NADH toward highly electronegative oxygen. The energy given up by the flow of electrons is used to pump hydrogen ions from the mitochondrial matrix into the intermembrane space. Oxygen captures the electrons in the very last step in electron transport. The last complex adds a pair of electrons to an oxygen atom and two hydrogen ions, forming water. The electron transport chain has used the energy of moving electrons to pump hydrogen ions into the intermembrane space. This buildup of hydrogen ions, like water behind a dam, stores the potential energy that was originally in the bonds of glucose molecules. The backed-up hydrogen ions give up their energy when they diffuse through a special protein in the membrane called ATP synthase. As hydrogen ions flow down their concentration gradient, ATP synthase captures their energy to make ATP. This mode of ATP production is called oxidative phosphorylation because it is powered by the transfer of electrons to oxygen.
Most of the energy harvested from organic molecules during glycolysis and the citric acid cycle is stored in NADH and FADH2. These molecules give up their high-energy electrons in the third phase of cellular respiration, oxidative phosphorylation, where most of the cell's ATP fuel is produced. The electron transport chain is an array of molecules, mostly proteins, built into the inner membrane of the mitochondrion. NADH gives up its high-energy electrons to the first complex in the electron transport chain. The electrons move from one member of the chain to the next, giving up their energy as they are pulled from NADH toward highly electronegative oxygen. The energy given up by the flow of electrons is used to pump hydrogen ions from the mitochondrial matrix into the intermembrane space. Oxygen captures the electrons in the very last step in electron transport. The last complex adds a pair of electrons to an oxygen atom and two hydrogen ions, forming water. The electron transport chain has used the energy of moving electrons to pump hydrogen ions into the intermembrane space. This buildup of hydrogen ions, like water behind a dam, stores the potential energy that was originally in the bonds of glucose molecules. The backed-up hydrogen ions give up their energy when they diffuse through a special protein in the membrane called ATP synthase. As hydrogen ions flow down their concentration gradient, ATP synthase captures their energy to make ATP. This mode of ATP production is called oxidative phosphorylation because it is powered by the transfer of electrons to oxygen.