Lipid Metabolism: Fatty Acid Oxidation for Energy Production
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Questions and Answers

Where does fatty acid oxidation occur in muscle?

  • Endoplasmic reticulum
  • Golgi apparatus
  • Mitochondria (correct)
  • Lysosomes
  • What is the approximate energy yield of fatty acid oxidation per mole compared to glucose?

  • Double of glucose
  • Half of glucose
  • More than twice of glucose (correct)
  • Twice of glucose
  • Why is glucose the preferred fuel during sudden bursts of muscular activity?

  • Because it provides more ATP
  • Because it is more readily available
  • Because it is a more complex molecule
  • Because it provides ATP rapidly (correct)
  • What is the role of insulin in relation to HSL?

    <p>Inhibits HSL</p> Signup and view all the answers

    What is the outcome of beta-oxidation of fatty acids?

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

    What is the name of the rare, autosomal recessive disorder caused by the accumulation of phytanic acid?

    <p>Refsum disease</p> Signup and view all the answers

    Why does phytanic acid undergo alpha-oxidation?

    <p>Because of the methyl group on its beta carbon</p> Signup and view all the answers

    What is the primary symptom of Refsum disease?

    <p>Neurologic symptoms</p> Signup and view all the answers

    What is the treatment for Refsum disease?

    <p>Dietary restriction</p> Signup and view all the answers

    What is the free energy change sufficient to generate in ATP production during fatty acid oxidation?

    <p>106 moles of ATP</p> Signup and view all the answers

    What is a characteristic of ketone bodies that makes them important sources of energy for peripheral tissues?

    <p>They are used in proportion to their concentration in the blood by extrahepatic tissues.</p> Signup and view all the answers

    Why is the liver unable to use ketone bodies as fuel?

    <p>It lacks the enzyme thiophorase.</p> Signup and view all the answers

    What is the result of excessive production of ketone bodies in diabetes mellitus?

    <p>Ketonemia and ketonuria occur.</p> Signup and view all the answers

    What is the origin of the fruity odor on the breath in diabetic ketoacidosis?

    <p>Increased production of acetone.</p> Signup and view all the answers

    What is the effect of ketone bodies on the pH of the blood?

    <p>They lower the pH of the blood.</p> Signup and view all the answers

    What is the consequence of excretion of glucose and ketone bodies in the urine?

    <p>Dehydration of the body.</p> Signup and view all the answers

    What is the effect of the increased number of H+ in a decreased volume of plasma?

    <p>It causes severe acidosis.</p> Signup and view all the answers

    What is a condition in which ketone bodies are produced in excess?

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

    What is the pKa of the carboxyl group of a ketone body?

    <p>About 4.</p> Signup and view all the answers

    What is the term for the condition in which the body's pH is lowered due to the production of ketone bodies?

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

    Study Notes

    Lipid Metabolism

    • Fatty acid oxidation occurs in mitochondria and is a major consumer of fat in muscle.
    • Fatty acids are more calorific than glucose, yielding approximately 38 kJ/mol compared to 16 kJ/mol for glucose.

    Fatty Acid Oxidation

    • Fatty acid oxidation provides quantitatively more ATP than glucose oxidation, but the rate of ATP generation is slower.
    • Insulin inhibits hormone-sensitive lipase (HSL) via dephosphorylation, while glucagon activates HSL via phosphorylation.
    • In the fed state, insulin is dominant, while in the fasted state, glucagon is dominant.

    β-Oxidation

    • β-oxidation is the catabolic process by which FA molecules are broken down in the mitochondria to generate acetyl-CoA.
    • Acetyl-CoA enters the TCA cycle and produces NADH and FADH2, which are coenzymes used in the electron transport chain.
    • β-oxidation is named as such because the β carbon of the FA undergoes oxidation to a second carbon (carbonyl carbon).

    α-Oxidation

    • Branched-chain, 20 carbon fatty acid, phytanic acid, undergoes α-oxidation because of the methyl group on its β carbon.
    • Refsum disease is a rare, autosomal recessive disorder caused by the accumulation of phytanic acid in the plasma and tissues.

    Ketone Bodies

    • Ketone bodies are important sources of energy for peripheral tissues.
    • Ketone bodies are produced in the liver during prolonged fasting and are used in proportion to their concentration in the blood.
    • Even the brain can use ketone bodies to help meet its energy needs if the blood levels rise sufficiently.

    Ketone Bodies in Diabetes Mellitus

    • Excessive production of ketone bodies in diabetes mellitus can lead to diabetic ketoacidosis.
    • A frequent symptom of diabetic ketoacidosis is a fruity odor on the breath, which results from increased production of acetone.
    • Ketoacidosis can cause severe acidosis due to the increased number of H+ circulating in a decreased volume of plasma.

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    Description

    Learn about the role of fatty acids in muscle energy production, comparing their energy yield with glucose, and understanding fatty acid oxidation in mitochondria.

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