FRANCIS LEROY & EDWIN VANDERMEEREN, BIOCOSMOS / SCIENCE PHOTO LIBRARY FRANCIS LEROY & EDWIN VANDERMEEREN, BIOCOSMOS / SCIENCE PHOTO LIBRARY
Electron transport chain in mitochondria, animation. ATP (adenosine triphosphate), for cellular processes. In eukaryotic cells it takes place on the inner membrane of mitochondria. A pair of electrons (blue dots) are transferred from NADH to the transmembrane protein NADH dehydrogenase (complex I, orange). The electrons flow to coenzyme Q (white), which carries them through the membrane to the cytochrome bc1 complex (complex III, red). The electrons are transferred to cytochrome c (yellow), a peripheral membrane protein bound to the outer surface of the inner membrane, which gives the electrons to cytochrome c oxidase (complex IV). This complex adds four electrons to oxygen, yielding two water molecules (blue). At each complex (I, III and IV) the transfer of electrons causes protons to be pumped from the matrix to the intermembrane space, establishing a proton gradient across the inner membrane. The protons flow down this gradient through ATP synthase (complex V, right), which synthesises adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate (Pi).
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