Easy - S12 Fatty Acid Catabolism
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Questions and Answers

Where does the conversion of fatty acyl-CoA to fatty acyl-carnitine take place?

  • Endoplasmic Reticulum
  • Mitochondria (correct)
  • Cytosol
  • Cytoplasm

    • Fatty acid oxidation occurs in the cytoplasm.

    False

    What is the role of glycerol kinase in glycolysis?

    Glycerol kinase activates glycerol at the expense of ATP

    Palmitic acid is a type of _______________________ acid.

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

    Match the following fatty acid-related processes with their locations:

    <p>Fatty acid synthesis = Cytosol Fatty acid oxidation = Mitochondria Glycerol phosphorylation = Cytosol Fatty acid transport = Mitochondrial membrane</p> Signup and view all the answers

    What is the result of fatty acid catabolism?

    <p>Energy production</p> Signup and view all the answers

    Glycerol is broken down to enter glycolysis.

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

    What is the role of carnitine in fatty acid transport?

    <p>Carnitine facilitates the transport of fatty acyl groups into the mitochondrial matrix.</p> Signup and view all the answers

    What is the purpose of malonyl-CoA in fatty acid metabolism?

    <p>To inhibit fatty acid breakdown during synthesis</p> Signup and view all the answers

    In seeds, fatty acids are used as a source of energy during germination.

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

    What is the byproduct of β-oxidation that is reduced in the presence of an isomerase?

    <p>1 NADH (and no FADH2)</p> Signup and view all the answers

    During fatty acid synthesis, acetyl-CoA is carboxylated by the enzyme ________________________ to produce malonyl-CoA.

    <p>acetyl-CoA carboxylase (ACC)</p> Signup and view all the answers

    Why does glucose oxidation produce more energy than fatty acid oxidation?

    <p>Because glucose oxidation is shorter</p> Signup and view all the answers

    Match the following statements with the correct process:

    <p>β-Oxidation = Breakdown of fatty acids for energy production Fatty Acid Synthesis = Synthesis of fatty acids from acetyl-CoA Ketogenesis = Production of ketone bodies in diabetic patients</p> Signup and view all the answers

    Carnitine acyltransferase I is inhibited by malonyl-CoA.

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

    What is the result of the formation of ketone bodies in diabetic patients?

    <p>Acetyl-CoA is converted to ketone bodies instead of being used in the TCA cycle.</p> Signup and view all the answers

    What is the primary advantage of fats over polysaccharides as an energy source?

    <p>Fatty acids carry more energy per carbon because they are more reduced</p> Signup and view all the answers

    Glucose and glycogen are used for long-term energy needs.

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

    What is the primary location of fat storage in vertebrates?

    <p>Under the skin, in adipocytes</p> Signup and view all the answers

    Triglycerides contain three fatty acid __________ and one glycerol.

    <p>acyl chains</p> Signup and view all the answers

    Match the following energy sources with their typical duration:

    <p>Glucose and glycogen = Short-term Fats = Long-term Protein = Not typically used for energy</p> Signup and view all the answers

    Fats are absorbed in the vertebrate large intestine.

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

    What is the percentage of our energy needs that come from dietary triacylglycerols?

    <p>About one third</p> Signup and view all the answers

    What is the purpose of glycerol kinase in the breakdown of fats?

    <p>To activate glycerol at the expense of ATP</p> Signup and view all the answers

    Fatty acid oxidation occurs in the mitochondria.

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

    What is the role of carnitine in fatty acid transport?

    <p>Carnitine is involved in the transport of fatty acids into the mitochondria.</p> Signup and view all the answers

    Fatty acid catabolism involves the breakdown of fatty acids into _______ units.

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

    Match the following fatty acid-related processes with their locations:

    <p>Fatty acid synthesis = Cytoplasm Beta-oxidation = Mitochondria Fatty acid transport = Mitochondria/Cytosol</p> Signup and view all the answers

    What is the result of fatty acid catabolism?

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

    Where is fat typically stored in vertebrates?

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

    Glucose is a more efficient source of energy than fats.

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

    What is the function of hormone-sensitive lipase (HSL) in fat metabolism?

    <p>To break down stored triacylglycerols into fatty acids and glycerol</p> Signup and view all the answers

    Glucagon increases lipolysis in adipose tissue.

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

    What is the result of hydrolysis of triacylglycerols?

    <p>Fatty acids and glycerol</p> Signup and view all the answers

    Epinephrine is often referred to as _______________________ 'we need energy now' hormone.

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

    Match the following hormones with their functions:

    <p>Glucagon = Increases glucose production in the liver Epinephrine = Increases lipolysis in adipose tissue Insulin = Decreases glucose production in the liver</p> Signup and view all the answers

    What is the product of lipolysis that can be used as energy by the body?

    <p>Fatty acids</p> Signup and view all the answers

    Where does β-oxidation of fatty acids occur?

    <p>Inside the mitochondria</p> Signup and view all the answers

    Small fatty acids (< 12 carbons) require a transporter to enter the mitochondria.

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

    What is the product of the first stage of fatty acid oxidation?

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

    Beta oxidation works in rounds, with each round removing one _______________________ moiety.

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

    Match the stages of fatty acid oxidation with their descriptions:

    <p>Stage 1 = Oxidation of acetyl-CoA into CO2 Stage 2 = Oxidative conversion of fatty acids into acetyl-CoA Stage 3 = ATP generation from NADH and FADH2</p> Signup and view all the answers

    What is the byproduct of β-oxidation that is reduced in the presence of an isomerase?

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

    Fatty acid synthesis occurs in the mitochondria.

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

    What is the role of carnitine in fatty acid transport?

    <p>to transport fatty acyl-CoA into the mitochondria</p> Signup and view all the answers

    Study Notes

    Fats and Triglycerides

    • Dietary triglycerides, regardless of plant or animal source, are composed of three fatty acid acyl chains and one glycerol molecule.
    • Fats are an important source of energy, providing about one-third of our energy needs.

    Advantages of Fats over Polysaccharides

    • Fatty acids carry more energy per carbon due to their higher reduction state, resulting in more electrons available for ATP production.
    • Fatty acids carry less water along because they are nonpolar.

    Storage Locations of Fats

    • In vertebrates, fats are stored in specialized cells called adipocytes, mainly located under the skin.
    • In plants, fats are stored in seeds.

    Fat Biosynthesis and Degradation Pathways

    • The pathways for fat biosynthesis and degradation are different and compartmentalized.

    Digestion, Mobilization, and Transport of Fats

    • Dietary fatty acids are absorbed in the small intestine.
    • Fats are transported and absorbed quickly.

    Oxidation of Fatty Acids

    • Fatty acids are oxidized through β-oxidation, producing energy.
    • Mono-unsaturated fatty acids require an isomerase to bypass the first enzyme of β-oxidation.

    Regulation of Fatty Acid Metabolism

    • High glucose levels inhibit fatty acid breakdown by preventing fatty acid entry into mitochondria.
    • Malonyl-CoA, an intermediate of fatty acid synthesis, inhibits carnitine acyltransferase I, blocking fatty acid breakdown.

    β-Oxidation in Plants

    • Seeds are rich in fatty acids, which are used as an energy source during germination.

    Ketone Bodies

    • Ketone bodies are formed when acetyl-CoA is converted to acetone, producing energy.
    • This occurs in diabetic patients with high glucose levels.

    Glycerol from Fats

    • Glycerol from fats enters glycolysis through glycerol kinase, which activates glycerol at the expense of ATP.

    Fatty Acids Conversion and Activation

    • Fatty acids are converted to fatty acyl-CoA in the cytoplasm through a series of reactions.
    • Fatty acyl-CoA is then transported into the mitochondria for β-oxidation.

    Fatty Acid Transport into the Mitochondria

    • Fatty acyl-CoA is converted to fatty acyl carnitine, which is transported into the mitochondria through a series of reactions.
    • Only carnitine is transported back out of the mitochondria.

    Glycerol from Fats

    • Glycerol gets cleaved and enters glycolysis through the action of glycerol kinase, which activates glycerol at the expense of ATP.
    • Glycerol is converted into an intermediate of glycolysis (Step 4).

    Fatty Acids

    • Fatty acids are converted to fatty acyl-CoA in the cytosol.
    • Fatty acyl-CoA is then cleaved and undergoes beta oxidation in the mitochondria.
    • Palmitic acid (C16) is a dominant carbon chain fatty acid.

    Fatty Acid Transport into the Mitochondria

    • Fatty acid transport into the mitochondria requires the conversion of fatty acyl-CoA to fatty acyl carnitine.
    • The carnitine transporter is an integral protein that replaces CoA with carnitine, allowing the fatty acid to be transported into the mitochondria.
    • Only carnitine can transport fatty acids across the mitochondrial membrane.
    • Small fatty acids (< 12 carbons) can diffuse freely across the mitochondrial membrane.

    Beta Oxidation of Fatty Acids

    • Beta oxidation of fatty acids occurs inside the mitochondria.
    • Fatty acid oxidation occurs in three stages:
    • Stage 1: oxidative conversion of fatty acids into acetyl-CoA, generating NADH.
    • Stage 2: oxidation of acetyl-CoA into CO2 via the citric acid cycle, generating NADH and FADH2.
    • Stage 3: ATP generation from NADH and FADH2 via the respiratory chain.

    Hydrolysis of Fats

    • Hydrolysis of triacylglycerols is catalyzed by lipases.
    • Hormone-sensitive lipase is regulated by hormones glucagon and epinephrine.
    • Glucagon and epinephrine increase lipolysis by releasing the second messenger cAMP, which activates hormone-sensitive lipase.
    • Lipase breaks the ester bond, releasing fatty acids and glycerol from stored triacylglycerols.

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