Chemiosmosis

• Aerobic Respiration: Chemiosmosis and Electron Transport Chain
• Electron Transport Chain: Products of Glycolysis and Krebs cycle are ATP, NADH, FADH.
• Electron Transport Chain:Electrons carried by NADH and FADH are transported to the inner mitochondrial membrane.
• The Transition Reaction stage of aerobic respiration results in 2 NADH and 6 ATP.
• The Krebs Cycle stage of aerobic respiration results in 2 ATP/GTP and 2 ATP.
• Glycolysis is the first stage of aerobic respiration and results in 2 ATP and 2 NADH.
• The Electron Transport Chain stage of aerobic respiration results in 4 ATP.
• The maximum ATP yield for the whole aerobic respiration process is 38 ATP molecules.
• Electron Transport Chain:Complex I, Complex II and Ubiquinone, Complex III, Complex IV, ETC and Proton Pumps are proteins that receive and transfer electrons from the oxidation of NADH.
• The table below summarizes the net ATP yield for the whole aerobic respiration process.
• Stages of aerobic respiration include Glycolysis, Transition Reaction, Krebs Cycle, and Electron Transport Chain.
• Electron Transport Chain:Electrons are then transferred to ubiquinone (labeled as Q), thus producing QH2.
• Every FADH2 is equivalent to two ATP molecules because its electrons will only move through complexes III and IV.
• Chemiosmosis involves the downhill transport of hydrogen ions from the intermembrane space to the matrix, providing energy to ATP synthase to phosphorylate ADP into ATP.
• A total of 34 ATP molecules are produced through electron transport chain and chemiosmosis.
• The energy from the released electrons is used to pump hydrogen ions from the matrix to the intermembrane space, generating a proton gradient.
• The electron transport chain consists of four multiprotein complexes embedded in the inner membrane of the mitochondrion where NADH and FADH2 are oxidized to release electrons.
• In terms of ATP synthesis, NADH is equivalent to three ATP molecules because its electrons will move through complexes I, III, and IV.
• Electron Transport Chain:Complex I, Complex II and Ubiquinone, Complex III, Complex IV, ETC and Proton Pumps are proteins that receive and transfer electrons from the oxidation of FADH.
• Complex III contains three molecules, namely, cytochrome b (Cyt b), Rieske center (2Fe-2S center), and cytochrome c1 (Cyt c1).
• The first electron released by QH2 is transferred to Rieske center to Cyt c1.
• Cyt c transfers electrons from complex III to complex IV.
• Q is converted into its reduced form semiquinone radical ion (Q–).
• When another QH2 arrives at the complex III, it is oxidized again to Q.
• One electron of QH2 is transferred to the Rieske center then to Cyt c1 and Cyt c.
• The second electron is transferred to Cyt b and then to Q–.
• Since Q– receives another electron, it becomes QH2.
• The QH2 molecule is eventually released to the inner membrane of the mitochondrion.
• The electron travels to CuA/CuA to Cyt a, and then to Cyt a3.