Lecture 21a
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Questions and Answers

What is the purpose of the electron transfer in the process described?

  • To convert succinate to fumarate by having FAD accept two electrons from succinate
  • To reduce two molecules of cytochrome c using two electrons from QH2
  • To transport four protons through the Q cycle to the Inter Membrane Space
  • To drive the expulsion of four protons per pair of electrons from the matrix (correct)

    • What is the role of Complex II (Succinate Dehydrogenase) in this process?

  • It reduces two molecules of cytochrome c using two electrons from QH2
  • It transports protons through the Q cycle to the Inter Membrane Space
  • It does not transport protons as part of the process
  • It accepts two electrons from succinate and passes them via iron-sulfur centers to ubiquinone (correct)

    • What is the role of Complex III (Ubiquinone:Cytochrome C Oxidoreductase) in this process?

  • It accepts electrons from succinate and passes them to ubiquinone
  • It reduces two molecules of cytochrome c using two electrons from QH2 (correct)
  • It does not transport protons as part of the process
  • It transports four protons through the Q cycle to the Inter Membrane Space

    • What is the role of Cytochrome C in this process?

    <p>It is a soluble heme-containing protein in the Inter Membrane Space that carries a single electron from Complex III to Complex IV</p> Signup and view all the answers

    How many electrons are carried by Cytochrome C in this process?

    <p>One electron</p> Signup and view all the answers

    What is the net result of the electron transfer process described?

    <p>All of the above</p> Signup and view all the answers

    What is the primary function of the cristae in mitochondria?

    <p>To increase the surface area for the electron transport chain and ATP synthase</p> Signup and view all the answers

    Which of the following statements about the chemiosmotic mechanism in mitochondria is correct?

    <p>Electrons move through the respiratory chain due to the high reduction potential of oxygen and low reduction potentials of substrates</p> Signup and view all the answers

    Where are the enzymes involved in the citric acid cycle located within the mitochondrion?

    <p>In the matrix</p> Signup and view all the answers

    What is the primary driving force for ATP synthesis in mitochondria?

    <p>The proton gradient across the inner mitochondrial membrane</p> Signup and view all the answers

    Which of the following statements about the mitochondrial matrix is correct?

    <p>It contains the enzymes involved in the citric acid cycle</p> Signup and view all the answers

    What is the overall free-energy change (ΔG'o) for the transfer of electrons from NADH to O2?

    <p>-220 kJ/mol of NADH</p> Signup and view all the answers

    What is the overall change in the redox potential (ΔE'o) for the transfer of electrons from NADH to O2?

    <p>1.14 V</p> Signup and view all the answers

    How many protons are pumped out of the matrix into the intermembrane space for each electron pair transferred from NADH to O2?

    <p>10</p> Signup and view all the answers

    What is the redox potential (E'o) for the O2/H2O redox pair?

    <p>0.816 V</p> Signup and view all the answers

    What is the redox potential (E'o) for the NAD+/NADH redox pair?

    <p>-0.320 V</p> Signup and view all the answers

    What is the free-energy change (ΔG'o) for the transfer of electrons from succinate to O2?

    <p>-151.5 kJ/mol of succinate</p> Signup and view all the answers

    What is the result of two electrons reducing one half oxygen molecule?

    <p>One water molecule</p> Signup and view all the answers

    How many protons are picked up from the matrix per four electrons in the process of reducing oxygen to water?

    <p>Four protons</p> Signup and view all the answers

    What is the role of Complex IV (cytochrome oxidase) in the electron flow and proton movements in the respiratory chain?

    <p>Transfers two electrons from reduced cytochrome c to half O2</p> Signup and view all the answers

    What is the total number of protons that flow from the matrix to the intermembrane space when a pair of electrons flow through Complexes I, III, and IV?

    <p>10 protons</p> Signup and view all the answers

    Which electron carriers pass two electrons to Complex III in the electron transport chain?

    <p>QH2 and cytochrome c</p> Signup and view all the answers

    How many protons are transferred to the intermembrane space when Complex IV transfers two electrons from reduced cytochrome c to half O2?

    <p>Four protons</p> Signup and view all the answers

    Which of the following statements about electron carriers in the electron transport chain (ETC) is correct?

    <p>Ubiquinone can act as a junction between one-electron and two-electron donors/acceptors.</p> Signup and view all the answers

    What is the primary function of the electron transport chain (ETC) protein complexes?

    <p>To pump protons out of the mitochondrial matrix, creating an electrochemical gradient.</p> Signup and view all the answers

    Which of the following statements about the redox centers in the ETC protein complexes is incorrect?

    <p>Iron-sulfur clusters can only accept one electron at a time.</p> Signup and view all the answers

    What is the role of ubiquinone (coenzyme Q) in the electron transport chain?

    <p>To shuttle electrons between one-electron and two-electron donors/acceptors.</p> Signup and view all the answers

    Which of the following statements about the reduction of ubiquinone is correct?

    <p>It requires two electrons and two protons, occurring in two steps via a semiquinone radical intermediate.</p> Signup and view all the answers

    What is the primary driving force for ATP synthesis in mitochondria?

    <p>The electrochemical potential created by the pumping of protons out of the matrix.</p> Signup and view all the answers

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