The electron transport chain and oxidative phosphorylation

• Where are electrons transferred in mitochondria?

  To the electron transport chain
• Why is the inner mitochondrial membrane important?

  It has a large surface area for reactions
• What are the components of the electron transport chain?Specialized protein complexes

  • 3 protein complexes (I, III, IV)
  • 1 complex on matrix side (II)
  • 2 mobile electron carriers (quinones, cytochrome)
• How do electrons flow in the electron transport chain?

  They flow spontaneously down a gradient
• What do NADH and FADH provide to the electron transport chain?

  Electrons
• How is ATP energy generated from electrons?

  Electron-motive force converts to proton motive force which is converted to phosphoryl transfer potential by ATP synthase
• What is the role of coenzyme Q?

  It carries electrons from NADH and FADH
• What is the function of Complex II in the electron transport chain?

  FADH is oxidised to FAD and 2 electrons are transferred via Fe-S clusters
• How does Complex II differ from Complex I in terms of ATP production?

  Complex II does not pump H+, less ATP produced
• What does Complex III do with electrons?

  It pumps 2 H+ into the intermembrane space
• What is cytochrome c?

  A small soluble protein in respiration
• What is the structure of cytochrome c?

  5 alpha helices in tertiary structure
• What does Complex IV require to function?

  2 haem and 3 copper ions
• What is produced when O2 is split in Complex IV?

  2 molecules of H2O
• What role do metal ion cofactors play in the electron transport chain?

  They shuttle and carry electrons
• How do metal ion cofactors behave during electron transfer?

  They cycle between oxidation states
• What are the key processes in the electron transport chain?

  1. Electrons transferred from NADH and FADH
  2. Electrons flow through protein complexes
  3. Proton motive force generated
  4. ATP synthase converts proton motive force to ATP
• how is the electron transfer gradient created?

  each complex/carrier has a lower free energy than the one before meaning the first carrier is easily oxidised (electron loss) and the final is easily reduced (electron gain)
• what does NADH from the citric acid cycle do?

  transport electrons to complex I
• what is the structure of Complex I?

  45 protein quaternary structure that spans into the membrane and mitochondrial matrix
• what is the process that occurs at Complex I?

  1. 2 electrons from NADH are transferred to FMN
  2. FMN is reduced to FMNH2
  3. FMNH2 transfers 2 electrons to a series of Fe-S clusters
  4. 2 electrons are transferred to coenzyme Q making is ubiquinone
• how many protons are pumped due to the process at complex I?

  4
• what does complex III require?

  cofactors - 3 x haem, Fe-S clusters
• what is the role of cytochrome c?

  carries 1 electron from complex III to complex IV
• where do the 8 H+ produced go at complex VI?

  4 are used to make water, 4 are pumped into the imtermembrane space
• what is complex V also known as?

  ATP synthase
• what do the 2 subunits of complex V do?

  proton conducting and catalytic (ADP + Pi -> ATP)
• how many H+ are produced for 2 NADH?

  10
• how many H+ are required for 1 ATP to be synthesized?

  3
• how many ATP are synthesized for each NADH

  2.5
• how many molecules of ATP does 1 glucose molecule produce?

  30