Fatty Acid Oxidation and Ketone Bodies
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Questions and Answers

Which fatty acid chain length does Malonyl CoA predominantly inhibit during the degradation process?

  • C14-C20
  • C13-C20 (correct)
  • C12-C18
  • C6-C12

    • Which statement is true regarding the energy yield from the beta oxidation of palmitate?

  • It yields 7 Acetyl CoA and 4 FADH2.
  • It undergoes 4 cycles resulting in 8 Acetyl CoA. (correct)
  • It produces 14 NAD+ molecules in total.
  • It involves 5 steps and results in 7 NADH.

    • What is produced from the oxidation of odd-chain fatty acids?

  • Acetyl CoA only
  • Both Acetyl CoA and Propionyl CoA
  • Propanoyl CoA
  • Propionyl-CoA (correct)

    • Which cofactor is required for converting Propionyl CoA into Methylmalonyl CoA?

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

    In which state does the liver convert excess Acetyl-CoA into ketone bodies?

    <p>During prolonged starvation</p> Signup and view all the answers

    What is the final product when Methylmalonyl CoA is converted in the presence of vitamin B12?

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

    What is a key difference between fatty acid synthesis and degradation?

    <p>Synthesis requires reducing equivalents while degradation produces them.</p> Signup and view all the answers

    Which ketone body is primarily expired through the lungs?

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

    What initial role does Carnitine acyltransferase-1 play in fatty acid metabolism?

    <p>It transfers FA-CoA to carnitine.</p> Signup and view all the answers

    Which enzyme directly inhibits Carnitine acyltransferase-1 activity?

    <p>Malonyl-CoA.</p> Signup and view all the answers

    What is produced during each cycle of beta-oxidation?

    <p>1 NADH, 1 FADH2, and 1 Acetyl-CoA.</p> Signup and view all the answers

    How many rounds of beta-oxidation are required for the complete oxidation of palmitate?

    <p>7 rounds.</p> Signup and view all the answers

    What is the general regulatory mechanism for beta-oxidation?

    <p>Substrate and cofactor availability regulate beta-oxidation.</p> Signup and view all the answers

    Which enzyme is specific for handling very long-chain fatty acids during beta-oxidation?

    <p>Very long-chain acyl-CoA dehydrogenase.</p> Signup and view all the answers

    Which of the following represents a key difference between fatty acid synthesis and degradation?

    <p>Synthesis adds acetyl-CoA while degradation releases it.</p> Signup and view all the answers

    What is the product of beta-oxidation that enters the TCA cycle?

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

    Which statement describes the role of high glucagon levels in metabolic processes during low insulin states?

    <p>High glucagon increases lipolysis, elevating plasma free fatty acids.</p> Signup and view all the answers

    What is a consequence of excessive ketogenesis in uncontrolled type 1 diabetes?

    <p>Depletion of the NAD+ pool impacting metabolism.</p> Signup and view all the answers

    How does the brain adapt to energy needs during fasting?

    <p>It begins utilizing ketone bodies after approximately one week of fasting.</p> Signup and view all the answers

    What condition is characterized by both ketonemia and ketonuria?

    <p>Diabetic ketoacidosis</p> Signup and view all the answers

    During beta-oxidation of palmitate, which enzyme is primarily responsible for the first oxidation step?

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

    Which metabolic pathway is directly influenced when the NAD+ pool is depleted?

    <p>TCA cycle</p> Signup and view all the answers

    What describes the metabolic fate of excess acetyl CoA during ketogenesis?

    <p>It accumulates and is used for ketone body production.</p> Signup and view all the answers

    What is the primary mechanism for the brain's inability to utilize fatty acids as an energy source?

    <p>Fatty acids cannot cross the blood-brain barrier (BBB).</p> Signup and view all the answers

    Study Notes

    Fatty Acid Oxidation and Ketone Bodies

    • LCAD is the enzyme that handles fatty acid chains with C13-C20 carbons.
    • MCAD handles chains with C6-C12 carbons.
    • SCAD handles chains shorter than C6.
    • Malonyl CoA inhibits CPT1 (Carnitine palmitoyl transferase-1) which is the rate-limiting enzyme in the transport of long-chain fatty acids across the mitochondrial membrane. Insulin also indirectly inhibits CPT1 by stimulating ACC.
    • The four steps in beta-oxidation are oxidation, Hydration, oxidation, and cleavage.
    • Each cycle of beta-oxidation produces 1 acetyl-CoA, 1 NADH, and 1 FADH2.
    • Propionyl-CoA is the unique product of odd-chain fatty acid oxidation.
    • Propionyl-CoA is converted to methylmalonyl-CoA and then succinyl-CoA, which enters the TCA cycle.
    • Biotin is required for the conversion of propionyl-CoA to methylmalonyl-CoA.
    • Vitamin B12 in its coenzyme form is required for the conversion of methylmalonyl-CoA to succinyl-CoA.
    • Methylmalonic aciduria is a condition caused by a deficiency in Vitamin B12.
    • Ketone bodies are synthesized in the liver during prolonged starvation.
    • Acetoacetate, β-hydroxybutyrate, and acetone are the three ketone bodies.
    • Acetone is expired by the lungs.
    • The brain begins to metabolize ketone bodies after a week of fasting because fatty acids cannot cross the blood-brain barrier.
    • Diabetic ketoacidosis occurs due to uncontrolled type 1 diabetes. High levels of fatty acids cause an increase in acetyl-CoA production, which depletes the NAD+ pool and slows down the TCA cycle.
    • This excessive acetyl-CoA is used to make ketone bodies.
    • Fruity odor breath is a common symptom of diabetic ketoacidosis due to the presence of acetone.
    • Carnitine is essential for the transport of fatty acids into the mitochondria.
    • Carnitine palmitoyl transferase-2 (CPT2) is located on the inner mitochondrial membrane and transfers fatty acyl-carnitine back to fatty acyl-CoA.
    • Beta-oxidation is the reverse process of fatty acid synthesis.
    • Four different fatty acyl-CoA dehydrogenases are involved in beta-oxidation, each specific for a different acyl chain length.
    • The rate of processing acetyl-CoA in the TCA cycle affects the rate of beta-oxidation.
    • VLCAD is the enzyme that handles very long chain fatty acids (C21 and longer).

    Summary of Fatty Acid Metabolism

    • Lipogenesis is the synthesis of fatty acids.
    • TAG synthesis is the synthesis of triacylglycerols.
    • Lipolysis is the breakdown of fatty acids.
    • Beta-oxidation is the process of breaking down fatty acids into acetyl-CoA.
    • Ketogenesis is the synthesis of ketone bodies.
    • Ketolysis is the breakdown of ketone bodies
    • Important Notes*
    • Fatty acid synthase is the key enzyme involved in the synthesis of fatty acids.

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    Lecture 24 Lipolysis and Beta Oxidation PDF

    Description

    This quiz covers the metabolic pathways of fatty acid oxidation and the formation of ketone bodies. Key enzymes, substrates, and the role of vitamins in these processes are highlighted. Test your knowledge on beta-oxidation and the specifics of different fatty acid chains.

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