Carbs 3
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What is the main function of the Electron Transport Chain (ETC)?

  • Produce metabolic water by combining electrons with O2 and H+. (correct)
  • Store excess energy in the form of NADH and FADH2.
  • Facilitate the breakdown of lipids and nucleotides.
  • Support cellular defense mechanisms via NADPH production.

    • Why are compounds that inhibit the proteins complexes of the ETC considered lethal?

  • They stimulate the production of excess NADPH, disrupting cellular defense mechanisms.
  • They disrupt the electron transfer process, leading to cell death. (correct)
  • They prevent the production of ATP in mitochondria.
  • They cause an uncontrolled breakdown of lipids and nucleotides.

    • What is the role of CoQ in the Electron Transport Chain?

  • Act as a proton pump in the mitochondria.
  • Assist in the breakdown of lipids and nucleotides.
  • Transport electrons between NADH and FADH2. (correct)
  • Generate NADPH for cellular defense mechanisms.

    • How is ATP produced in mitochondria through the ETC?

    <p>By pumping H+ ions across the inner mitochondrial membrane.</p> Signup and view all the answers

    What happens during oxidation in the ETC?

    <p>Electrons are removed from electron donors.</p> Signup and view all the answers

    Which part of the ETC creates an electrochemical gradient by pumping H+ ions?

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

    What happens during reduction in the ETC?

    <p>Electrons are gained by electron receptors.</p> Signup and view all the answers

    How does the ETC use free energy released by electrons?

    <p>To pump H+ ions and create an electrochemical gradient.</p> Signup and view all the answers

    What is the primary function of the Pentose Phosphate Pathway (PPP) in the cell?

    <p>To produce ribose residues for nucleotide and nucleic acid biosynthesis</p> Signup and view all the answers

    Which of the following tissues has the highest activity of the Pentose Phosphate Pathway (PPP)?

    <p>Liver and adipose tissue</p> Signup and view all the answers

    Which of the following physiological processes is NOT directly dependent on NADPH?

    <p>ATP production in the mitochondria</p> Signup and view all the answers

    What is the primary function of NADPH in the synthesis of nitric oxide (NO)?

    <p>To provide the reducing power for the nitric oxide synthase enzyme</p> Signup and view all the answers

    How does NADPH contribute to the maintenance of cellular redox homeostasis?

    <p>By regulating the activity of antioxidant enzymes</p> Signup and view all the answers

    Which of the following is NOT a major function of NADPH in physiological processes?

    <p>Facilitating the transport of oxygen across cell membranes</p> Signup and view all the answers

    What is the primary reason for the high activity of the Pentose Phosphate Pathway (PPP) in the lactating mammary gland?

    <p>To generate NADPH for the synthesis of milk fats</p> Signup and view all the answers

    What is the effect of uncouplers on the relationship between oxidation and phosphorylation?

    <p>Uncouplers dissociate oxidation from phosphorylation</p> Signup and view all the answers

    What is the role of NADPH in cellular defense mechanisms?

    <p>NADPH is used as a reducing agent in antioxidant defense systems</p> Signup and view all the answers

    Which of the following is a function of the Pentose Phosphate Pathway (PPP)?

    <p>To generate NADPH for cellular defense mechanisms</p> Signup and view all the answers

    What is the primary function of NADPH in physiological processes?

    <p>To act as a reducing agent in various metabolic processes</p> Signup and view all the answers

    Which of the following is a potential function of the respiratory burst in immune cells?

    <p>To generate reactive oxygen species for pathogen defense</p> Signup and view all the answers

    How does the action of uncouplers differ from the action of respiratory inhibitors?

    <p>Uncouplers dissociate oxidation from phosphorylation, while respiratory inhibitors generate heat during hibernation</p> Signup and view all the answers

    What is the main function of the Cori Cycle?

    <p>Convert lactate into glucose in the liver</p> Signup and view all the answers

    What is the primary storage organ for glycogen in the body?

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

    Which enzyme is responsible for starting the glycogen chain during glycogenesis?

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

    What is the alternate name for the Pentose Phosphate Pathway (PPP)?

    <p>Hexose Monophosphate Shunt</p> Signup and view all the answers

    Which hormone stimulates glycogenolysis and inhibits glycogenesis?

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

    What is the main source of substrate for gluconeogenesis?

    <p>Lactate from anaerobic glycolysis</p> Signup and view all the answers

    Which enzyme elongates the glycogen chain during glycogenesis?

    <p>Glycogen synthase</p> Signup and view all the answers

    What is the primary location of gluconeogenesis in the body?

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

    Which of the following substrates is NOT used in gluconeogenesis?

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

    Why is gluconeogenesis not considered the reverse of glycolysis?

    <p>Gluconeogenesis uses different enzymatic pathways than glycolysis.</p> Signup and view all the answers

    Which of the following hormones stimulates gluconeogenesis?

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

    What is the primary function of the TCA cycle in the context of gluconeogenesis?

    <p>To convert glucogenic amino acids into oxaloacetate</p> Signup and view all the answers

    Which of the following molecules is NOT a substrate for gluconeogenesis?

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

    What is the primary purpose of gluconeogenesis in the body?

    <p>To maintain plasma glucose levels between meals</p> Signup and view all the answers

    Which of the following amino acids is NOT considered a glucogenic amino acid?

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

    What is the primary effect of UNCOUPLERS on cellular respiration?

    <p>Generate heat without ATP production</p> Signup and view all the answers

    Which of the following substances inhibits Complex IV in the electron transport chain?

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

    How do UNCOUPLERS affect the relationship between oxidation and phosphorylation?

    <p>Dissociate oxidation from phosphorylation</p> Signup and view all the answers

    Where does gluconeogenesis primarily occur in the body?

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

    What is the main function of ATP synthase in oxidative phosphorylation?

    <p>ATP synthesis</p> Signup and view all the answers

    Which of the following is an inhibitor of Complex I in the electron transport chain?

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

    What is the purpose of generating heat without ATP production in cells?

    <p>Maintain body temperature</p> Signup and view all the answers

    What primarily regulates OXPHOS based on the energy needs of the cell?

    <p>ATP/ADP ratio</p> Signup and view all the answers

    Which hormone stimulates gluconeogenesis and inhibits insulin in the context of glucose metabolism?

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

    What is the primary substrate used for gluconeogenesis from TAG breakdown?

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

    Which compound is responsible for creating an electrochemical gradient during OXPHOS?

    <p>Proton (H+) ions</p> Signup and view all the answers

    What is the primary role of ATP synthase in cellular respiration?

    <p>Generating ATP</p> Signup and view all the answers

    Which amino acid is NOT considered a substrate for gluconeogenesis?

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

    Which of the following compounds is known to uncouple electron transport from ATP synthesis in mitochondria?

    <p>DNP (2,4-Dinitrophenol)</p> Signup and view all the answers

    What inhibits gluconeogenesis during glucose metabolism?

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

    What is the main function of ATP synthase in the context of oxidative phosphorylation?

    <p>Creating an electrochemical gradient by pumping H+ ions</p> Signup and view all the answers

    Which pathway provides an important source of substrate for gluconeogenesis?

    <p>Cori Cycle</p> Signup and view all the answers

    What is the primary reason for the high activity of the Pentose Phosphate Pathway (PPP) in certain metabolic processes?

    <p>Generating NADPH for biosynthetic reactions and antioxidant defense</p> Signup and view all the answers

    Which of the following is NOT considered an inhibitor of Oxidative Phosphorylation?

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

    How do uncouplers affect the relationship between electron transport and ATP synthesis in mitochondria?

    <p>Decrease ATP production despite increased electron transport</p> Signup and view all the answers

    Which enzyme is responsible for initiating the glycogen chain during glycogenesis?

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

    'Glucose 6-phosphate' as a substrate in Glucose metabolism is primarily associated with which pathway?

    <p>Pentose Phosphate Pathway</p> Signup and view all the answers

    What is the primary function of ATP synthase in the Electron Transport Chain (ETC)?

    <p>It converts the energy released from the electrochemical gradient into the phosphorylation of ADP to produce ATP.</p> Signup and view all the answers

    Which of the following is a primary function of the Pentose Phosphate Pathway (PPP) in the cell?

    <p>To produce NADPH for reductive biosynthesis and cellular defense mechanisms.</p> Signup and view all the answers

    What is the primary role of gluconeogenesis in the body?

    <p>To convert amino acids and other non-carbohydrate precursors into glucose.</p> Signup and view all the answers

    How do uncouplers differ from respiratory inhibitors in their effects on the Electron Transport Chain (ETC)?

    <p>Uncouplers disrupt the coupling between oxidation and phosphorylation, while respiratory inhibitors block specific complexes in the ETC.</p> Signup and view all the answers

    Which part of the Electron Transport Chain (ETC) is responsible for pumping H+ ions across the inner mitochondrial membrane to create an electrochemical gradient?

    <p>Complex I (NADH dehydrogenase)</p> Signup and view all the answers

    How does the Electron Transport Chain (ETC) use the free energy released by the transfer of electrons?

    <p>The free energy is used to pump H+ ions across the inner mitochondrial membrane, creating an electrochemical gradient.</p> Signup and view all the answers

    Why are compounds that inhibit the protein complexes of the Electron Transport Chain (ETC) considered lethal?

    <p>They block the transfer of electrons through the ETC, preventing the reduction of oxygen to water.</p> Signup and view all the answers

    What is the primary function of the Pentose Phosphate Pathway (PPP) in the cell?

    <p>Generation of NADPH for reductive biosynthesis</p> Signup and view all the answers

    Which of the following tissues has the highest activity of the Pentose Phosphate Pathway (PPP)?

    <p>Adipose tissue</p> Signup and view all the answers

    What is the primary role of NADPH in the respiratory burst process?

    <p>Production of reactive oxygen species (ROS) like H2O2</p> Signup and view all the answers

    Which of the following is NOT a substrate for gluconeogenesis?

    <p>Fatty acids</p> Signup and view all the answers

    What is the primary function of ATP synthase?

    <p>Synthesis of ATP from ADP and Pi</p> Signup and view all the answers

    How does the action of uncouplers differ from the action of respiratory inhibitors?

    <p>Uncouplers disrupt the proton gradient, while inhibitors block electron flow</p> Signup and view all the answers

    What is the primary regulation point of the TCA cycle?

    <p>The conversion of α-ketoglutarate to succinyl-CoA</p> Signup and view all the answers

    Study Notes

    Electron Transport Chain (Respiratory Chain)

    • Passes electrons from NADH and FADH2 to protein complexes and mobile electron carriers (CoQ and cytochrome C)
    • Electrons ultimately combine with O2 and H+ to form H2O (metabolic water)
    • Requires O2, making it the major consumer of oxygen in mammalian cells
    • 4 transmembrane enzymatic complexes + 2 mobile electron carriers (CoQ, cytochrome C)
    • Electron-transporting groups contain iron, sulfur, copper
    • All are proteins except for CoQ
    • Free energy released by electrons is used to pump H+
    • Electrons are transferred from electron donor to electron receptor
    • Oxidation → electrons are removed, Reduction → electrons are gained
    • Phosphorylation of ADP to ATP:
      • Pumps H+ from matrix across inner mitochondrial membrane at complexes I, III, and IV
      • Creates an electrochemical gradient
      • Energy created moves ATP synthase
    • Generates NADPH for reductive biosynthesis of lipids (fatty acids, cholesterol, and steroids)
    • Provides ribose residues for nucleotide and nucleic acid biosynthesis (ATP, NAD+, FAD, RNA, and DNA)

    The Pentose Phosphate Pathway (PPP)

    • Occurs in cell cytosol, no ATP is consumed or generated
    • High activity in:
      • Liver and adipose tissue: biosynthesis of fatty acids from acetyl-CoA
      • Endocrine tissues: synthesis of cholesterol and steroid hormones
      • Lactating mammary gland: production of milk fats and proteins
      • Mature erythrocyte, lens and cornea: glutathione production (oxidative damage protection)

    NADP+/NADPH

    • Important source of electrons (reducing/oxidizing agent)
    • Contributes to maintenance of cellular redox homeostasis
    • Reduces cytochrome P450 (drug metabolism in liver)
    • Synthesizes Nitric Oxide (NO) for smooth muscle relaxation, neurotransmission, and bactericidal activity
    • Involved in lipogenesis, synthesis of steroids and fatty acids
    • Participates in respiratory burst in phagocytic cells (NADPH-oxidase)

    Glycogen Metabolism

    • Glycogenesis: stores glucose as glycogen
      • Main stores in liver (up to 10% of liver weight) and skeletal muscle (up to 1% of muscle weight)
    • Glycogenolysis: glycogen mobilization from glycogen stores
      • Occurs when blood glucose levels are low (i.e., fasting)
    • Glycogen synthesis occurs in cell cytosol, each molecule contains around 60,000 glucose residues and is highly hydrophilic
    • Important enzymes for synthesis: glycogenin (primer), glycogen synthase (elongate chain), and branching enzyme
    • Glycogen storage diseases are associated with enzyme deficiencies
    • Prolonged use of steroids can cause glycogen storage abnormalities
    • Regulation: insulin (anabolic) stimulates glycogenesis and inhibits glycogenolysis, while glucagon (and epinephrine) (catabolic) stimulates glycogenolysis and inhibits glycogenesis

    Cori Cycle and Gluconeogenesis

    • Cori cycle: lactate produced by anaerobic glycolysis is transported to the liver and converted to glucose (gluconeogenesis pathway)
      • Prevents lactic acidosis during anaerobic conditions in muscle
      • Important source of substrate for gluconeogenesis
    • Gluconeogenesis: production of glucose from non-sugar molecules
      • Supplies plasma glucose needs between meals and during prolonged fasting
      • Continuous process in carnivores and ruminants
      • Hormone-controlled (stimulated by glucagon and epinephrine, inhibited by insulin)
      • Substrates: lactate, pyruvate, glycerol, and glucogenic amino acids (e.g., alanine, arginine, aspartate)

    ATP Synthase and Oxidative Phosphorylation Inhibitors and Uncouplers

    • ATP synthase: multi-subunit enzyme that rotates to synthesize ATP from ADP and Pi
    • Oxidative phosphorylation inhibitors:
      • Complex I: barbiturate, insecticide (rotenone)
      • Complex II: malonate, carboxin, and TTFA (Fe-chelating agent)
      • Complex III: dimercaprol, antimycin
      • Complex IV: hydrogen sulfide (H2S), carbon monoxide (CO), and cyanide
    • Uncouplers dissociate oxidation from phosphorylation, generating heat instead of ATP

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    Carbohydrates 3 VP 2024 PDF

    Description

    Learn about the significance of the Pentose Phosphate Pathway (PPP) in providing NADPH for reductive biosynthesis of lipids and ribose residues for nucleotide and nucleic acid biosynthesis. Understand where PPP occurs and its high activity in specific tissues such as liver, adipose tissue, and endocrine tissues.

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