Glucose Metabolism and Pyruvate Oxidation
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Questions and Answers

What is the primary method used to infer metabolic heat production in indirect calorimetry?

  • Measuring body temperature
  • Respiratory gas exchange (correct)
  • Tracking caloric intake
  • Weight gain assessment

    • Which of the following is NOT a pro of using indirect calorimetry?

  • User-friendly
  • Requires minimal assumptions (correct)
  • Can be used on active animals
  • Equipment can be portable

    • What does the respiratory quotient (RQ) of 0.7 indicate about the type of fuel being oxidized?

  • There is no fuel oxidation taking place
  • Carbohydrates are being oxidized
  • Lipids are the primary fuel source (correct)
  • Proteins are being metabolized

    • How does the oxidation of fats compare to carbohydrates in terms of oxygen requirement?

    <p>Requires 14.9% - 18.7% more oxygen than carbohydrates</p> Signup and view all the answers

    What is hypothesized regarding the hovering VO2 of a hummingbird when fasting compared to when fed?

    <p>It is 15-19% greater when fasting</p> Signup and view all the answers

    What is the primary characteristic of saturated fatty acids?

    <p>They lack double bonds between carbon atoms.</p> Signup and view all the answers

    What is a key feature of fatty acid oxidation (β-Oxidation)?

    <p>It is a process that requires oxygen.</p> Signup and view all the answers

    Which tissue cannot directly metabolize fatty acids but can utilize ketones?

    <p>Vertebrate brain</p> Signup and view all the answers

    What is the final electron acceptor in mitochondrial oxidative metabolism?

    <p>Oxygen (O2)</p> Signup and view all the answers

    What primarily determines the production of phosphocreatine?

    <p>The ratio of concentration of substrates/products</p> Signup and view all the answers

    Which component of the electron transport system (ETS) is part of the inner mitochondrial membrane?

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

    Which of the following statements about gluconeogenesis is correct?

    <p>It helps maintain blood glucose levels during fasting.</p> Signup and view all the answers

    What does the TCA cycle primarily generate within the mitochondria?

    <p>Reducing equivalents</p> Signup and view all the answers

    Which method measures ATP turnover rather than ATP consumption?

    <p>31P-NMR spectroscopy</p> Signup and view all the answers

    What drives ATP synthesis in oxidative phosphorylation?

    <p>Proton motive force (Δp)</p> Signup and view all the answers

    Which molecule serves as an alternate high-energy phosphate-containing molecule?

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

    What is a primary disadvantage of using 31P-NMR spectroscopy?

    <p>It requires subjects to be restrained or anesthetized.</p> Signup and view all the answers

    What is a unique feature of the cnidarian parasite regarding oxygen dependence?

    <p>It does not require oxygen for survival.</p> Signup and view all the answers

    What does Hess's Law state about the energy released from fuel breakdown?

    <p>It remains constant regardless of the pathways taken.</p> Signup and view all the answers

    What is produced when acetyl CoA enters the TCA cycle?

    <p>Carbon dioxide and reducing equivalents</p> Signup and view all the answers

    What is the primary advantage of direct calorimetry?

    <p>It is quite accurate under many conditions.</p> Signup and view all the answers

    In direct calorimetry, how is the heat production of the subject measured?

    <p>By observing the melting of surrounding ice due to animal heat.</p> Signup and view all the answers

    What types of energy production does direct calorimetry account for?

    <p>Both aerobic and anaerobic energy production</p> Signup and view all the answers

    What aspect of the subject can direct calorimetry affect?

    <p>Physical constraints imposed by the equipment</p> Signup and view all the answers

    What is a result of metabolic pathways integrating efficiently?

    <p>Optimized use of metabolic fuels.</p> Signup and view all the answers

    What are the end products of glycolysis?

    <p>2 ATP, 2 pyruvate, 2 NADH</p> Signup and view all the answers

    Which statement about pyruvate is correct?

    <p>Pyruvate can be oxidized to form acetyl CoA in mitochondria.</p> Signup and view all the answers

    What is required for glycolysis to continue after producing NADH?

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

    Where does glycolysis take place within the cell?

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

    How does NADH produced in glycolysis enter the mitochondria?

    <p>It cannot enter mitochondria directly from the cytoplasm</p> Signup and view all the answers

    What happens to pyruvate in the presence of oxygen?

    <p>It is oxidized to acetyl CoA by PDH.</p> Signup and view all the answers

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

    <p>It donates electrons to the electron transport chain.</p> Signup and view all the answers

    Which molecule is produced from the dehydrogenation of pyruvate by PDH?

    <p>Acetyl CoA</p> Signup and view all the answers

    What is the primary role of the lactate dehydrogenase (LDH) enzyme?

    <p>Converting lactate back to pyruvate</p> Signup and view all the answers

    Which shuttle is primarily associated with mammals and most vertebrates?

    <p>Malate-aspartate shuttle</p> Signup and view all the answers

    What happens to NADH in the absence of oxygen?

    <p>It accumulates in the cytoplasm.</p> Signup and view all the answers

    Which compound is produced from pyruvate during anaerobic metabolic conditions?

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

    What is a key characteristic of lipids?

    <p>They are hydrophobic and do not dissolve in water.</p> Signup and view all the answers

    Which type of lipid has a ring structure?

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

    When oxygen becomes available after an anaerobic state, what can lactate be converted back into?

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

    What is the typical ATP yield from lactate during anaerobic metabolism?

    <p>2 ATP</p> Signup and view all the answers

    Which of these pathways produces the highest ATP yield among the listed options?

    <p>Propionate formation</p> Signup and view all the answers

    Which shuttle is specifically noted for invertebrate animals?

    <p>α-glycerophosphate shuttle</p> Signup and view all the answers

    Study Notes

    Glucose Metabolism

    • Glucose metabolism can start with glucose imported from the bloodstream or from glycogen.
    • Glycolysis occurs in the cytoplasm and doesn't require oxygen.
    • Glucose + 2ADP + 2NAD+ → 2ATP + 2pyruvate + 2NADH + 2H+
    • Glycolysis produces intermediates for synthesis of various molecules (carbohydrates, nucleic acids, amino acids, and fatty acids).
    • Pyruvate is the end product of glycolysis.
    • Pyruvate can be used in other catabolic processes.
    • NADH in the cytoplasm needs to enter the mitochondria.

    Oxidation of Pyruvate

    • Pyruvate is converted to acetyl CoA inside the mitochondria by pyruvate dehydrogenase (PDH).
    • Pyruvate is oxidized (loses electrons) in this process.
    • NADH generated from this reaction can be used in the electron transport chain.

    Oxidation of NADH

    • NADH generated from glycolysis or other processes can donate energy to the electron transport chain.
    • The electron transport chain is located in the mitochondria, whereas NADH is in the cytoplasm.
    • NADH needs to be transported into the mitochondria for electron transport chain use
    • Alternative transport methods exist, such as the glycerol-3 phosphate shuttle and the malate-aspartate shuttle.

    Oxidation of NADH in the Absence of Oxygen

    • If oxygen is not present, NADH cannot be rapidly used by mitochondria.
    • NADH can be oxidized in the cytoplasm to produce lactate instead.
    • Lactate is produced when pyruvate and NADH combine in the absence of oxygen.
    • Humans can use lactate to produce energy, and can enter the process again when oxygen is present.

    Lipids

    • All lipids are hydrophobic (do not dissolve in water).
    • Lipids are used in energy metabolism, cell structure, and signalling.

    Fatty Acids

    • Fatty acids have a carbon chain ending with a carboxyl group.
    • Saturated fatty acids have no double bonds.
    • Unsaturated fatty acids have one or more double bonds.

    Fatty Acid Oxidation

    • Fatty acids are used for energy.
    • They are a more dense energy source than carbohydrates.
    • Energy from fatty acids is released through β-oxidation in the mitochondria.

    Ketones

    • Some tissues cannot metabolize fatty acids and can metabolize ketones instead; these tissues can include vertebrate brains and shark muscles.

    Oxidative Metabolism

    • Acetyl CoA enters the tricarboxylic acid (TCA) cycle via the mitochondria.
    • The TCA cycle produces reducing equivalents (NADH and FADH2) and GTP.
    • Oxidative phosphorylation converts reducing equivalents to ATP.
    • The electron transport system (ETS) is part of oxidative phosphorylation.
    • Reactive oxygen species (ROS) are generated during Oxidative metabolism.
    • The process produces ATP, heat, water, and ROS.

    ATP Synthesis

    • ADP + Pi → ATP
    • Proton motive force (Δψ) creates a gradient across the mitochondria membrane.
    • F₁F₀ ATPase utilizes the Δψ to produce ATP.
    • Two processes (oxidation and phosphorylation) are functionally coupled.
    • Phosphocreatine is an alternate high-energy molecule for storing and transferring phosphate.

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    BIOB34 Tutorial - Glucose Metabolism PDF

    Description

    This quiz covers essential concepts regarding glucose metabolism, including glycolysis, the conversion of pyruvate to acetyl CoA, and the oxidation of NADH. Explore key processes and reactions that occur in the cytoplasm and mitochondria, and understand how energy is generated through these metabolic pathways.

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