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Questions and Answers

What is a clinical problem caused by a defect in the carnitine shuttle system?

  • Respiratory failure
  • Poor exercise tolerance (correct)
  • Muscle cramps
  • Hypoglycemia

    • What is the byproduct of β-oxidation of fatty acids?

  • Triacylglycerols
  • Ketone bodies
  • Glycogen
  • Acetyl-CoA (correct)

    • Where does the β-oxidation of fatty acids occur?

  • Lysosome
  • Endoplasmic reticulum
  • Cytosol
  • Mitochondria (correct)

    • What is required for the β-oxidation of fatty acids?

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

    What is the end product of fatty acid synthesis?

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

    Where do fatty acids enter the cell?

    <p>Extracellular space</p> Signup and view all the answers

    What is the first step in the degradation of fatty acids?

    <p>Activation of FAS</p> Signup and view all the answers

    What is the vitamin contained in Coenzyme A?

    <p>Vitamin B5</p> Signup and view all the answers

    What is the energy source required for the reaction of linking fatty acids to Coenzyme A?

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

    What is the purpose of the carnitine shuttle system in fatty acid metabolism?

    <p>To regulate the rate of fatty acid oxidation</p> Signup and view all the answers

    What is the molecule that inhibits the transport of activated fatty acids into mitochondria?

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

    What is the product of the reaction between fatty acids and Coenzyme A?

    <p>Fatty acid-CoA</p> Signup and view all the answers

    What is the enzyme that catalyzes the reaction between fatty acids and Coenzyme A?

    <p>Fatty acyl-CoA synthase</p> Signup and view all the answers

    What is a characteristic of lipids?

    <p>They contain less O but more H</p> Signup and view all the answers

    What is the function of triacylglycerols?

    <p>Fuel storage and insulation</p> Signup and view all the answers

    What is the product of esterification of glycerol with three fatty acids?

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

    What is the breakdown of triacylglycerols known as?

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

    What is cholesterol used for in the body?

    <p>Membranes and steroid hormone synthesis</p> Signup and view all the answers

    What type of compounds are vitamins A, D, E, and K?

    <p>Fatty acid derivatives</p> Signup and view all the answers

    What is the class of lipids that includes bile acids and bile salts?

    <p>Hydroxy-methyl-glutaric acid derivatives</p> Signup and view all the answers

    Where are triglycerides primarily stored in the body?

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

    What hormones promote the storage of triglycerides?

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

    What is the primary function of triglycerides in the body?

    <p>To store energy for prolonged aerobic exercise and stress situations</p> Signup and view all the answers

    What is the process by which dietary triglycerides are broken down?

    <p>Hydrolysis by pancreatic lipase</p> Signup and view all the answers

    What is the fate of glycerol derived from the hydrolysis of dietary triglycerides?

    <p>It enters the bloodstream and is transported to the liver for metabolism</p> Signup and view all the answers

    What is a characteristic property of fatty acids?

    <p>They are hydrophobic and highly reduced</p> Signup and view all the answers

    Where does the lipogenesis pathway occur?

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

    What is the source of acetyl-CoA in lipogenesis?

    <p>Carbohydrate and amino acid catabolism</p> Signup and view all the answers

    What is the role of ATP in lipogenesis?

    <p>Energy source for the reaction</p> Signup and view all the answers

    What is the role of NADPH in lipogenesis?

    <p>Reducing agent for the reaction</p> Signup and view all the answers

    What is the source of NADPH in lipogenesis?

    <p>Pentose phosphate pathway</p> Signup and view all the answers

    What is the enzyme that catalyzes the production of citrate from acetyl-CoA?

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

    What is the role of citrate in the regulation of acetyl-CoA carboxylase?

    <p>Activator of the enzyme</p> Signup and view all the answers

    What is the fate of excessive carbohydrate and protein consumed in excess of requirements?

    <p>Esterification to triacylglycerols</p> Signup and view all the answers

    What is the effect of insulin on lipogenesis?

    <p>Activates the enzyme</p> Signup and view all the answers

    Study Notes

    Clinical Significance of Carnitine Shuttle

    • Defects in the carnitine shuttle system can cause clinical problems, including poor exercise tolerance and high levels of triacylglycerols in muscle cells.
    • This system is crucial for regulating the rate of fatty acid oxidation by controlling their entry into mitochondria.

    Fatty Acid Oxidation

    • Fatty acid oxidation occurs in the mitochondria, where fatty acids are broken down into acetyl-CoA.
    • The oxidation process involves the removal of a C2 unit (acetate) from the fatty acid, which occurs repeatedly until only two carbon atoms remain.
    • The overall reaction for the β-oxidation of stearic acid (C-18) is: C17H35COOH + 9 CoA + ATP + 8 FAD + 8 NAD+ + 8 H2O → 9 CH3CO-COA (acetyl-CoA) + AMP + 2 Pi + 8 FADH2 + 8 NADH + 8 H+
    • β-oxidation of fatty acids requires mitochondrial NAD+ and FAD, and cannot occur in the absence of oxygen.

    Fatty Acid Activation

    • Fatty acid activation is the first step in fatty acid degradation, and involves linking fatty acids to coenzyme A (CoA).
    • The reaction requires ATP and is catalyzed by fatty acyl CoA synthase.
    • The activated fatty acid is then transported into the mitochondria for oxidation.

    Lipid Metabolism

    • Lipids are diverse and hydrophobic, containing CHO (and P and N in phospholipids).
    • They are more reduced than carbohydrates and are present in the body in different forms.
    • Classes of lipids include fatty acid derivatives, hydroxy-methyl-glutaric acid derivatives, and vitamins.

    Triacylglycerols

    • Triacylglycerols (TG) are the major dietary and storage lipid in the body.
    • They consist of three fatty acids esterified to glycerol.
    • TG are stored in adipose tissue and serve as a fuel source for prolonged aerobic exercise, stress situations, and during pregnancy.

    Metabolism of TG

    • Stage 1 of TG metabolism involves hydrolysis of dietary lipids by pancreatic lipase in the small intestine.
    • Glycerol derived from TG hydrolysis is transported to the liver and metabolized.
    • Triacylglycerol synthesis involves the reaction of glycerol and fatty acids.

    Lipogenesis

    • Fatty acids are synthesized from acetyl-CoA (derived from carbohydrate and amino acid catabolism) in the cytoplasm.
    • The pathway requires ATP and NADPH and is regulated by allosteric regulation, insulin, and anti-insulin hormones.
    • Excessive carbohydrate and protein consumption lead to esterification to triacylglycerols for storage in adipose tissue, which can cause obesity and associated problems.

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    Description

    This quiz covers the clinical significance of carnitine shuttle in the mitochondrial fatty acid transport system, its effects on exercise tolerance and fatty acid oxidation. Learn about the beta-oxidation of fatty acids and its process in the mitochondria.

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