Fat Absorption in Digestive System
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Questions and Answers

Where does most of the fat absorption occur?

  • Duodenum (correct)
  • Stomach
  • Jejunum
  • Ileum
  • By which point in the small intestine are almost all digested lipids absorbed?

  • End of the jejunum
  • End of the duodenum
  • Beginning of the duodenum
  • Mid-jejunum (correct)
  • What is the stage of food in the small intestine where fat absorption occurs?

  • Digestive enzymes
  • Bolus
  • Food fragments
  • Chyme (correct)
  • Which part of the small intestine is responsible for the majority of fat absorption?

    <p>The first section of the small intestine</p> Signup and view all the answers

    What is the primary site of lipid absorption in the small intestine?

    <p>Proximal duodenum</p> Signup and view all the answers

    What is the role of translocase in the cell?

    <p>To assist in moving another molecule across a cell membrane</p> Signup and view all the answers

    What amino acids are used to synthesize carnitine?

    <p>Lysine and methionine</p> Signup and view all the answers

    Where is carnitine synthesized in the body?

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

    What is the general term for a protein that assists in moving another molecule across a cell membrane?

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

    How many ATPs are generated when NADH is oxidized in the electron transport chain?

    <p>2.5</p> Signup and view all the answers

    What is the end product of the cleavage reaction catalyzed by thiolase?

    <p>Acetyl-CoA and an acyl-CoA shorter by two carbon atoms</p> Signup and view all the answers

    What is the role of thiolase in the process?

    <p>To cleave beta-ketoacyl-CoA into two products</p> Signup and view all the answers

    What is the change in the number of carbon atoms in the acyl-CoA after the cleavage reaction?

    <p>Decreased by two</p> Signup and view all the answers

    In which step of the process does the cleavage reaction occur?

    <p>Step 4</p> Signup and view all the answers

    What is the product of the oxidation of acyl-CoA by an acyl-CoA dehydrogenase?

    <p>Δ2-trans enoyl-CoA</p> Signup and view all the answers

    What is the coenzyme for the dehydrogenase in the first reaction?

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

    How many ATP molecules are produced when FADH2 is oxidized in the electron transport chain?

    <p>1.5</p> Signup and view all the answers

    What is the enzyme responsible for the oxidation of acyl-CoA?

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

    What is the reduced form of FAD?

    <p>FADH2</p> Signup and view all the answers

    What is the product of 8 acetyl CoA in terms of ATP?

    <p>80 ATP</p> Signup and view all the answers

    How many high energy bonds are utilized in the initial activation reaction?

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

    What is the net ATP yield from one molecule of palmitate?

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

    What is the ATP yield from 7 FADH2?

    <p>10.5 ATP</p> Signup and view all the answers

    What is the ATP yield from 7 NADH?

    <p>17.5 ATP</p> Signup and view all the answers

    Study Notes

    Fat Absorption

    • Most of the fat absorption occurs in the duodenum, with almost all digested lipids absorbed by the time the chyme reaches the mid-jejunum.

    Carnitine

    • Carnitine is synthesized from lysine and methionine in the liver and kidney.
    • Translocase is a protein that assists in moving molecules across a cell membrane.

    Fatty Acid Oxidation

    • Step 1: Oxidation by FAD occurs through acyl-CoA dehydrogenase, producing Δ2-trans enoyl-CoA and reducing FAD to FADH2.
    • FADH2 generates 1.5 ATP molecules when oxidized in the electron transport chain.
    • NADH generates 2.5 ATP molecules when oxidized in the electron transport chain.

    Cleavage

    • β-Ketoacyl-CoA is split at the β-carbon by thiolase, producing acetyl-CoA and an acyl-CoA shorter by two carbon atoms.
    • Each molecule of palmitate yields 8 acetyl-CoA molecules.

    Energy Yield

    • The energy yield from one molecule of palmitate is:
      • 80 ATP from 8 acetyl-CoA molecules
      • 10.5 ATP from 7 FADH2 molecules
      • 17.5 ATP from 7 NADH molecules
    • Gross total energy yield is 108 ATP, with a net yield of 106 ATP after subtracting 2 high-energy bonds used in the initial activation reaction.

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    Description

    Learn about the process of fat absorption in the digestive system, specifically in the duodenum and jejunum.

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