cristae many oxysomes (F particles) are present which have electron transport carriers. According to Peter Mitchell’s Chemiosmotic theory this electron transport is coupled to ATP synthesis. Electron and hydrogen(proton) transport takes place across four multiprotein complexes(I-IV). They are .
Complex-I (NADH dehydrogenase). It contains a flavoprotein(FMN) and associated with non-heme iron Sulphur protein (Fe-S). This complex is responsible for passing electrons and protons from mitochondrial NADH ( Internal) to Ubiquinone (UQ). NADH H UQ NAD UQH In plants , an additional NADH dehydrogenase ( External) complex is present on the outer surface of inner membrane of mitochondria which can oxidise cytosolic NADH H .
Because mitochondrial inner membrane cannot allow NADH molecules directly into the matrix. Ubiquinone (UQ) or Coenzyme Quinone (CoQ) is a small, lipid soluble electron, proton carrier located within the inner membrane of mitochondria. . Complex-II (Succinic dehydrogenase) It contains FAD flavoprotein is associated with non-heme iron Sulphur (Fe-S) protein.
This complex receives electrons and protons from succinate in Krebs cycle and is converted into fumarate and passes to ubiquinone. Succinate UQ → Fumarate UQH . Complex-III (Cytochrome bc complex) This complex oxidises reduced ubiquinone (ubiquinol) and transfers the electrons Oxidation of one molecule of NADH H gives rise to molecules of ATP and oxidation of one molecule FADH produces molecules of ATP within a mitochondrion. But cytoplasmic NADH H yields only two ATPs through external NADH d e h y d r o g e n a s e .
Therefore, two reduced coenzyme (NADH H ) molecules from glycolysis being extra mitochondrial will yield ATP molecules instead of ATPs (Figure . ). The Mechanism of mitochondrial ATP synthesis is based on Chemiosmotic hypothesis. According to this theory electron carriers present in the inner mitochondrial membrane allow for the transfer of protons (H ).
For the production of single ATP, protons (H ) are needed. The terminal oxidation of external