Cellular Respiration (Electron Transport Chain)

Summary

Key Points

• —The electron transport chain involves several protein complexes and two mobile carriers that work together to synthesize ATP. 0:59
• —The process begins when two electrons from NADH are passed into the NADH dehydrogenase complex, simultaneously pumping one hydrogen ion for each electron. 1:42
• —Ubiquinone, a mobile transfer molecule, then moves these electrons from the NADH dehydrogenase complex to the cytochrome b-c1 complex. 1:54
• —Each electron is subsequently transferred from the cytochrome b-c1 complex to cytochrome c, with one hydrogen ion pumped as each electron moves. 2:11
• —The next major step occurs in the cytochrome oxidase complex, which requires four electrons that interact with a molecular oxygen molecule and eight hydrogen ions. 2:16
• —Within the cytochrome oxidase complex, four electrons, four hydrogen ions, and the molecular oxygen are used to form two water molecules. 2:30
• —The remaining four hydrogen ions are pumped across the membrane, creating a hydrogen ion gradient. 2:39
• —The potential energy stored in this hydrogen ion gradient is harnessed by ATP synthase to produce ATP from ADP and inorganic phosphate. 2:46
• —In biological systems, many electron transport cycles occur simultaneously to continuously maintain the proton gradient necessary for ATP synthesis. 3:18