L32: Oxidative Phosphorylation

• Where does oxidative phosphorylation take place?

  In the mitochondria
• What is the primary process of oxidative phosphorylation?

  ATP is formed as a result of electron transfer from NADH or FADH₂ to O₂
• What are the reduced cofactors involved in oxidative phosphorylation?

  NADH and FADH₂
• How many NADH and FADH₂ are produced from glucose to AcetylCoA conversion?

  4 NADH and 2 AcetylCoA
• Why can't cytosolic NADH enter the mitochondrial matrix directly?

  The inner mitochondrial membrane is impermeable to NADH
• What are the two shuttles that transport electrons from NADH into the mitochondrial matrix?

  The glycerol phosphate shuttle and the malate shuttle
• What is the consequence of using the glycerol phosphate shuttle for NADH?

  Only 6 H⁺ are pumped instead of 10, resulting in less ATP production
• In which tissues is the malate shuttle primarily used?

  In the heart and liver
• How do ADP and inorganic phosphate (P_i) enter the mitochondrial matrix?

  Through two antiporters: P_i-OH- antiporter and ATP-ADP antiporter
• What is the role of the respiratory complexes in oxidative phosphorylation?

  They transfer electrons from NADH/FADH₂ to O₂ and pump protons into the intermembrane space
• What is the standard free energy change (ΔG°’) for the electron transport chain?

  ΔG°’ = -220 kJ/mol
• What is the function of Complex I in the electron transport chain?

  It oxidizes NADH and transfers electrons to ubiquinone
• What is the role of cytochrome C in Complex III?

  It carries one electron at a time from the iron-sulfur complexes to oxygen
• What must cytochrome C oxidase do with oxygen during its function?

  It must hold onto oxygen until fully reduced to water
• What is the result of the reaction catalyzed by Complex II?

  No protons are pumped across the membrane
• What are respiratory super-complexes and their advantage?

  They are complexes that form super-complexes for more efficient electron transfer
• How is ATP synthesized during oxidative phosphorylation?

  By utilizing the proton gradient generated by electron transport
• What did Peter Mitchell propose in the chemiosmotic theory?

  The primary energy-conserving event is the generation of a proton-motive force across the inner mitochondrial membrane
• What does the proton-motive force generate?

  A concentration gradient and a transmembrane potential
• What is the role of Complex V (ATP synthase) in ATP synthesis?

  It couples proton pumping with ATP synthesis
• How many protons are pumped per NADH and FADH₂ oxidized?

  ~10 protons per NADH and ~6 protons per FADH₂
• How many ATP are generated per glucose molecule during respiration?

  ~30 ATP
• What is the efficiency of respiration based on the given ΔG values?

  52%
• What regulates the flow of electrons from NADH to O₂?

  The need for ATP, determined by the level of ADP