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Electron Transport Chain Inhibition
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Electron Transport Chain Inhibition

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@VeritableJadeite

Questions and Answers

What is required for ADP/ATP translocation across the inner mitochondrial membrane?

  • Presence of oxygen
  • Energy from electron transport
  • Exchange of ADP with ATP (correct)
  • Blockade of complex I

    • What type of cofactor does complex I contain?

  • Iron-sulfur centers and cytochromes
  • Cyanide and copper ions
  • Flavin cofactor and heme centers
  • Flavin cofactor and iron-sulfur centers (correct)

    • Which complex is inhibited by cyanide ion (CN−)?

  • Complex IV (correct)
  • Complex I
  • Complex II
  • Complex III

    • What is a requirement for electron transport to occur in the mitochondrial matrix?

    <p>ADP must be present</p> Signup and view all the answers

    How does cyanide affect the cytochrome c oxidase?

    <p>It competes with oxygen for binding</p> Signup and view all the answers

    Which of the following components is part of complex III?

    <p>Cytochrome b and c1</p> Signup and view all the answers

    What is true about the treatment of cyanide poisoning?

    <p>Cyanide binding is reversible if treated early.</p> Signup and view all the answers

    Which statement correctly describes the process of coupled respiration in mitochondria?

    <p>It involves the cooperation of electron transport and ATP synthesis.</p> Signup and view all the answers

    Which lipoprotein is most likely to be elevated in a patient experiencing steatorrhea?

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

    What symptom is NOT typically associated with steatorrhea?

    <p>Hemorrhaging in the gastrointestinal tract</p> Signup and view all the answers

    In which stage might steatorrhea present without symptoms?

    <p>Early stages</p> Signup and view all the answers

    Which fat-soluble vitamin deficiency is least likely to occur in a patient with steatorrhea?

    <p>Vitamin C</p> Signup and view all the answers

    What is primarily transported by chylomicrons after dietary intake?

    <p>Cholesterol and triglycerides</p> Signup and view all the answers

    What is a common manifestation observed in children with severe steatorrhea?

    <p>Muscle wasting</p> Signup and view all the answers

    Where do chylomicrons enter circulation after being assembled in the intestinal mucosa?

    <p>Left subclavian vein</p> Signup and view all the answers

    What type of diarrhea is associated with fat malabsorption leading to steatorrhea?

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

    What is the main effect of atractyloside on the ADP/ATP translocase?

    <p>It inhibits ADP transport into the mitochondria.</p> Signup and view all the answers

    How does the mitochondrial membrane affect proton movement?

    <p>It is impermeable to protons.</p> Signup and view all the answers

    What is the consequence of inhibiting ATP synthase with oligomycin?

    <p>Buildup of protons in the intermembrane space.</p> Signup and view all the answers

    What role does the proton gradient play in the electron transport chain?

    <p>It is crucial for ATP synthesis.</p> Signup and view all the answers

    Which process is directly halted due to inhibition of the part of the electron transport chain between complexes III and IV?

    <p>ATP formation via ATP synthase.</p> Signup and view all the answers

    Which of the following correctly describes a result of proton extrusion into the intermembrane space?

    <p>Development of a proton motive force.</p> Signup and view all the answers

    What is the primary function of the electron transport chain?

    <p>To generate a proton gradient for ATP synthesis.</p> Signup and view all the answers

    Which statement about oxygen's role in the electron transport chain is correct?

    <p>Oxygen acts as the final electron acceptor in the chain.</p> Signup and view all the answers

    Which medication can convert oxyhemoglobin to methemoglobin, thus increasing competition for cyanide binding?

    <p>Nitrite ion (NO2−)</p> Signup and view all the answers

    What is the primary role of cytochrome a/a3 in the presence of competitive inhibitors?

    <p>To facilitate electron transfer</p> Signup and view all the answers

    What effect does increasing the percentage of oxygen breathed have on competition with cyanide?

    <p>Increases competition for cytochrome a/a3</p> Signup and view all the answers

    Which component of the electron transport chain (ETC) is primarily affected by cyanide poisoning?

    <p>Cytochrome oxidase</p> Signup and view all the answers

    Which of the following statements about methemoglobin is correct?

    <p>It contains iron in the Fe3+ oxidation state.</p> Signup and view all the answers

    Which component of the electron transport chain is responsible for transferring electrons to oxygen?

    <p>Cytochrome oxidase</p> Signup and view all the answers

    What is the primary consequence of cyanide binding to cytochrome a/a3?

    <p>Disruption of electron transport</p> Signup and view all the answers

    Which of the following medications may NOT compete with cyanide for binding to cytochrome oxidase?

    <p>Sodium nitroprusside</p> Signup and view all the answers

    What is the primary function of bile produced in the liver?

    <p>To emulsify lipids in the intestines</p> Signup and view all the answers

    What will happen to fat when Sudan III dye is added to it in the presence of water?

    <p>It will form a red layer above the water</p> Signup and view all the answers

    Which condition is specifically associated with the inability to absorb bile acids due to distal ileal resection?

    <p>Ileal resection</p> Signup and view all the answers

    What type of obstruction is referred to by cholestasis?

    <p>Obstruction in the biliary duct</p> Signup and view all the answers

    What does the term emulsification refer to in the context of lipid digestion?

    <p>Mixing lipids with bile for easier absorption</p> Signup and view all the answers

    Which of the following is a consequence of primary sclerosing cholangitis (PSC)?

    <p>Obstruction of bile flow</p> Signup and view all the answers

    Which laboratory result indicates the presence of triglycerides in a stool sample?

    <p>The sample stains red with Sudan III dye</p> Signup and view all the answers

    What is a common result of small intestinal bacterial overgrowth (SIBO)?

    <p>Increased bile acid deconjugation</p> Signup and view all the answers

    Study Notes

    Electron Transport Chain Inhibition

    • Inhibition can occur between complexes III and IV or between complex IV and mitochondria, impacting electron transport, ATP formation, or ADP/ATP translocation.
    • Proton pumping is essential for creating a proton gradient across the inner mitochondrial membrane, allowing ATP synthesis.
    • A proton gradient develops due to mitochondrial membrane's impermeability to protons, driving proton flow through ATP synthase.

    Role of Inhibitors

    • Atractyloside inhibits ADP/ATP translocase, preventing ADP from entering mitochondria while stopping ATP export, leading to a failure in ATP production.
    • Oligomycin directly inhibits ATP synthase, causing proton accumulation in the intermembrane space and cessation of electron transfer.
    • Cyanide ion (CN−) is a potent inhibitor of complex IV, competing with oxygen for binding sites on cytochrome c oxidase.

    Mechanism of Cyanide Poisoning

    • Cyanide binding to cytochrome a/a3 prevents electron transfer to oxygen, disrupting cellular respiration.
    • Treatment involves enhancing oxygen levels to outcompete cyanide binding and administering nitrite ion, which converts hemoglobin to methemoglobin to further compete with cyanide.

    Steatorrhea

    • Defined as increased fat excretion in stools, characterized by bulky, pale, foul-smelling, and oily stools.
    • Can be asymptomatic in early stages; children may experience growth failure and delayed puberty due to fat malabsorption.
    • Causes include primary biliary cholangitis, primary sclerosing cholangitis, ileal resection, or bacterial overgrowth.

    Significance of Chylomicrons

    • Chylomicrons transport dietary cholesterol and triglycerides from the intestine to the bloodstream via the lymphatic system.
    • They are assembled in the intestinal mucosa, entering circulation at the left subclavian vein.

    Diagnostic Tests for Steatorrhea

    • Sudan III dye test identifies fat in stools; lipid presence stains red, indicating fat malabsorption.
    • In cases of steatorrhea, oil separates and floats in the solution due to lower density, forming a visible layer above water.

    Bile Production

    • Bile, produced in the liver, is crucial for fat digestion and absorption, delivered through the biliary duct to the duodenum.

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    Description

    This quiz explores the mechanisms of inhibition in the electron transport chain, focusing on the roles of various inhibitors like cyanide, atractyloside, and oligomycin. Understand how these inhibitors affect ATP production and the proton gradient essential for cellular respiration.

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