Biology Electron Transport Chain Quiz
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Questions and Answers

What is the primary role of NADH dehydrogenase in the electron transport chain?

  • To convert ubiquinone to FMNH2
  • To accept protons from the mitochondrial matrix
  • To transfer electrons from NADH to ubiquinone (correct)
  • To produce ATP directly

    • Which of the following describes coenzyme Q?

  • An enzyme that catalyzes ATP formation
  • A lipid-soluble electron carrier with a long isoprenoid tail (correct)
  • A type of cytochrome involved in ATP synthesis
  • A proton pump embedded in the mitochondrial membrane

    • How does the iron in cytochromes function within the electron transport chain?

  • It is reversibly converted between ferric and ferrous states (correct)
  • It is involved in the synthesis of NADH
  • It catalyzes the reaction of ADP to ATP
  • It binds to oxygen permanently

    • What forms after NADH is oxidized by NADH dehydrogenase?

    <p>FMNH2 and free protons</p> Signup and view all the answers

    What component is NOT part of the electron transport chain discussed?

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

    Which structure within NADH dehydrogenase is essential for transferring hydrogen atoms?

    <p>Iron-sulfur centers</p> Signup and view all the answers

    Which option accurately describes the conversion of cytochrome iron during electron transport?

    <p>It alternates between oxidized and reduced forms</p> Signup and view all the answers

    Where does coenzyme Q get its hydrogen atoms from?

    <p>From both FMNH2 and FADH2</p> Signup and view all the answers

    Which enzyme complex is directly involved in the oxidation of succinate?

    <p>Succinate dehydrogenase</p> Signup and view all the answers

    What is the primary function of cytochrome a + a3 within the electron transport chain?

    <p>To produce water as a byproduct.</p> Signup and view all the answers

    How do site-specific inhibitors affect the electron transport chain?

    <p>They block the passage of electrons.</p> Signup and view all the answers

    What occurs to electron carriers located before a site-specific inhibitor?

    <p>They become reduced.</p> Signup and view all the answers

    What type of reaction is always associated with oxidation in redox pairs?

    <p>Reduction.</p> Signup and view all the answers

    What is the role of standard reduction potential (E°) in redox pairs?

    <p>It determines the tendency to lose or gain electrons.</p> Signup and view all the answers

    Which molecule acts as an electron acceptor in the electron transport chain?

    <p>Oxygen.</p> Signup and view all the answers

    What happens to electrons as they move through the electron transport chain?

    <p>They produce free energy.</p> Signup and view all the answers

    What forms when cytochrome a + a3 reacts with molecular oxygen?

    <p>Water.</p> Signup and view all the answers

    What does NAD+ gain during a redox reaction?

    <p>Hydride ions.</p> Signup and view all the answers

    Which of the following statements about electron transport is true?

    <p>Free energy is released during the transfer of electrons.</p> Signup and view all the answers

    What is the primary function of the inner mitochondrial membrane?

    <p>Being impermeable to most ions and small molecules</p> Signup and view all the answers

    What are the structures called that increase the surface area of the inner mitochondrial membrane?

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

    Which complex in the inner mitochondrial membrane catalyzes ATP synthesis?

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

    What role do dehydrogenases play in the formation of NADH?

    <p>They remove two hydrogen atoms from their substrate.</p> Signup and view all the answers

    Which component is NOT part of the electron transport chain?

    <p>NAD+</p> Signup and view all the answers

    Which redox pair has the most positive standard reduction potential (E°)?

    <p>1/2 O2/H2O</p> Signup and view all the answers

    Which protein carrier accepts electrons from electron donors in the electron transport chain?

    <p>Coenzyme Q</p> Signup and view all the answers

    What is the standard free energy change (ΔG°) when one electron is transferred from NADH to cytochrome c?

    <p>-52,580 cal/mol</p> Signup and view all the answers

    What approximately composes fifty percent of the mitochondrial matrix?

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

    How many ATP can be produced from the transport of electrons from NADH to oxygen?

    <p>3</p> Signup and view all the answers

    What are the protruding spheres attached to the inner membrane known as?

    <p>Inner membrane particles</p> Signup and view all the answers

    What does the chemiosmotic hypothesis primarily describe?

    <p>The coupling of electron transport to ATP production</p> Signup and view all the answers

    What metal is commonly involved in the electron transport chain proteins?

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

    Which compound is a strong reducing agent from the provided standard reduction potentials?

    <p>NAD+/NADH</p> Signup and view all the answers

    What is the Faraday constant (F) value used in calculating ΔG°?

    <p>23,062 cal/volt * mol</p> Signup and view all the answers

    What is the primary byproduct of oxygen's role in the electron transport chain?

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

    What is formed when metabolic intermediates donate electrons to NAD+ and FAD?

    <p>NADH and FADH2</p> Signup and view all the answers

    Where is the electron transport chain located within the mitochondrion?

    <p>Inner mitochondrial membrane</p> Signup and view all the answers

    What role does the electron transport chain play in ATP production?

    <p>Pumps protons to create a proton gradient</p> Signup and view all the answers

    Which complex in the electron transport chain accepts electrons from NADH?

    <p>Complex I</p> Signup and view all the answers

    What is the end product of the electron transport chain when electrons are transferred to oxygen?

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

    How does the movement of electrons through the electron transport chain affect free energy?

    <p>Free energy is lost as electrons move</p> Signup and view all the answers

    What is the coupling process associated with ATP synthesis in oxidative phosphorylation?

    <p>Movement of electrons driving proton pumping</p> Signup and view all the answers

    Which component of the electron transport chain has the highest reduction potential?

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

    What is the consequence of the proton gradient created by the electron transport chain?

    <p>It drives ATP synthesis by ATP synthase</p> Signup and view all the answers

    Which of the following is not a component of the electron transport chain?

    <p>FADH2-Succinate reductase</p> Signup and view all the answers

    Study Notes

    Electron Transport Chain

    • Complex V is not illustrated; it plays a role in ATP synthesis.
    • NAD+ is reduced to NADH, generating a free proton (H+) during the process.
    • NADH Dehydrogenase (Complex I) transfers hydrogen atoms to ubiquinone, using FMN as a coenzyme and possesses iron-sulfur centers for electron transfer.
    • Coenzyme Q (Ubiquinone) is a ubiquitous quinone that accepts hydrogen atoms from both NADH dehydrogenase and FADH2.
    • Cytochromes are components of the electron transport chain, containing heme groups with iron. They facilitate electron transfer by changing oxidation states between Fe3+ and Fe2+.
    • Cytochrome a + a3 is significant as it can directly interact with molecular oxygen, converting transported electrons and protons into water.
    • Site-Specific Inhibitors can obstruct electron flow by binding to electron transport chain components, affecting redox reactions and leading to reduced carriers upstream and oxidized carriers downstream.
    • Electrons are transferred from donors to acceptors, releasing free energy throughout the process. They can be carried as hydride ions to NAD+, hydrogen atoms to other coenzymes, or solely as electrons to cytochromes.

    Bioenergetics and Oxidative Phosphorylation

    • The inner mitochondrial membrane is rich in proteins (50%), crucial for electron transport and oxidative phosphorylation.
    • The membrane is convoluted into structures called cristae, enhancing surface area for metabolic reactions.

    Structures within the Mitochondria

    • ATP Synthase complexes protrude into the mitochondrial matrix, facilitating ATP synthesis.
    • The matrix is protein-rich, housing enzymes for metabolic pathways, including the TCA cycle, and containing NAD+, FAD, ADP, and inorganic phosphate (Pi) needed for ATP production.
    • Mitochondrial RNA and DNA (mtRNA and mtDNA) along with ribosomes are also present in the matrix.

    Organization of the Electron Transport Chain

    • Comprises five enzyme complexes (I to V) embedded in the inner mitochondrial membrane.
    • Complexes I to IV function in electron transport, while Complex V is responsible for ATP synthesis.
    • Electron carriers, such as coenzyme Q and cytochrome c, shuttle electrons between complexes, maintaining a flow dictated by reduction potentials.

    Reactions in the Electron Transport Chain

    • All chain members besides coenzyme Q are proteins functioning as enzymes, with various metal-containing cofactors (iron, copper) essential for their activity.

    Formation of NADH

    • NAD+ is reduced to NADH via dehydrogenases that oxidize substrates by removing hydrogen atoms.

    Energy Production and Electron Transport

    • Energy-rich substrates, such as glucose, are oxidized ultimately leading to CO2 and water production.
    • NADH and FADH2 donate electrons to the electron transport chain, where energy is released and partial ATP synthesis occurs via oxidative phosphorylation.

    Standard Reduction Potential (E°)

    • Electrons flow from carriers with lower to higher reduction potentials, showcasing a defined order that enhances the efficiency of the electron transport chain.

    Change in Free Energy (ΔG°)

    • ΔG° values correlate with E° variations, facilitating the conversion of energy from electron transport into usable chemical energy for ATP synthesis.

    Standard Free Energy of ATP Hydrolysis

    • The hydrolysis of ATP releases -7300 cal/mol, while electron transfer from NADH yields approximately 52,580 cal, sufficient for producing multiple ATP molecules.

    Oxidative Phosphorylation and Chemiosmotic Hypothesis

    • In oxidative phosphorylation, the transport of electrons triggers ATP synthesis indirectly by creating a proton gradient across the inner mitochondrial membrane.
    • The Chemiosmotic Hypothesis asserts that the free energy from electron transport is harnessed to drive ATP production through the movement of protons (H+) across membranes, coupling electron flow to ATP synthesis.

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    Description

    Test your knowledge on the Electron Transport Chain, focusing on the role of NADH and the enzymes involved. This quiz covers key concepts such as the function of Complex I and the transfer of protons. Enhance your understanding of mitochondrial processes.

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