Electron Transport System (ETS)

 All NADH+H+ Produced during Glycolysis & Krebs cycle is oxidized by NADH-dehydrogenase and electrons are transported to Ubiquinone(UQ)via FMN.
 In ETS, , Molecular Oxygen (O2)acts as terminal electron acceptor.
 Electrons from NADH+H+ is transported through FMN, UQ (Hydrogen Carrier, Cytochromes(b,C1,C,a-a3) and finally to O2 which takes 2H+ from matrix and form H2O.
 During transport of electron, proton (H+) is pumped by UQ to inter membrane space from matrix causing formation of proton gradient (due to increase in protons in inter membrane space and decrease in matrix).
 Breaking of this gradient and return of these protons(H+)through ATP synthase/ Fo-F1 particle/ oxysomes located in inner membrane cause synthesis of ATP.
 Since oxidation of NADH+H+ is the cause of formation of proton gradient and ATP synthesis thereupon, so this method of ATP synthesis is called as oxidative phosphorylation.
 Return of 2H+ from inter membrane space to matrix through ATP synthase release sufficient energy to synthesise one ATP molecule.
 On oxidation of 1 molecule of NADH+H+ pumps 6H+, therefore it produces 3 ATP molecules while oxidation of FADH2 pumps only 4H+, so it produces 2 ATP molecules.