Glycogen Metabolism Quiz
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Questions and Answers

What is the active form of glucose involved in glycogen synthesis?

  • Glucose-6-phosphate
  • UDP-glucose (correct)
  • Glucose-1-phosphate
  • Sugar nucleotides
  • What type of glycosidic bonds are present in glycogen at branching points?

  • $\alpha(1\rightarrow4)$ and $\alpha(1\rightarrow6)$ (correct)
  • $\alpha(1\rightarrow4)$ and $\beta(1\rightarrow6)$
  • $\beta(1\rightarrow4)$ and $\alpha(1\rightarrow4)$
  • $\beta(1\rightarrow4)$ and $\alpha(1\rightarrow6)$
  • What is the rate-limiting step in glycogen synthesis?

  • Formation of branching points
  • Formation of glucose-6-phosphate
  • Formation of $\alpha(1\rightarrow4)$ glycosidic bonds (correct)
  • Formation of UDP-glucose
  • What enzyme catalyzes branching in glycogen?

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

    What is the product of glycogen breakdown by glycogen phosphorylase?

    <p>Glucose-1-phosphate</p> Signup and view all the answers

    What is the primary linkage between glucose units in the main chain of glycogen?

    <p>α-1,4 glycosidic bonds</p> Signup and view all the answers

    Which enzyme is responsible for the breakdown of glucose units from the non-reduced end of glycogen?

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

    Where does intense glycogen synthesis occur?

    <p>Liver and muscle tissue</p> Signup and view all the answers

    What is the substrate of glycogen synthesis?

    <p>UDP-glucose</p> Signup and view all the answers

    How is glycogen breakdown in muscle different from that in the liver?

    <p>Glycogen is broken down to glucose 6-phosphate in muscle, and to free glucose in the liver</p> Signup and view all the answers

    Which enzyme converts glucose-1-phosphate to glucose-6-phosphate in cells?

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

    What is the enzyme responsible for hydrolyzing glucose-6-phosphate to free glucose in the liver?

    <p>Glucose-6-phosphatase</p> Signup and view all the answers

    Which hormone increases the synthesis of glycogen in the liver and skeletal muscle?

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

    What happens to glycogen synthase when it is phosphorylated?

    <p>It becomes inactive</p> Signup and view all the answers

    Why can't muscle glycogen increase blood sugar levels?

    <p>Lack of glucose-6-phosphatase in muscles</p> Signup and view all the answers

    Study Notes

    Glycogen Metabolism: Key Concepts

    • Free glucose from glycogenolysis in the liver is released into the bloodstream for other tissues' use.
    • Liver glycogen stores fluctuate, increasing in the well-fed state and depleting during fasting.
    • Muscle glycogen is minimally affected by short fasting periods and moderately decreased in prolonged fasting.
    • Sugar nucleotides are crucial for various hexose transformation and polymerization reactions.
    • UDP-Glucose, a sugar nucleotide, is formed by a condensation reaction between a nucleoside triphosphate and a sugar phosphate.
    • Glycogen consists of α(1→4) glycosidic bonds and contains α(1→6) glycosidic bonds at branching points.
    • Glycogen synthesis begins with glucose-6-phosphate, which is formed from free glucose by specific enzymes.
    • The synthesis of glycogen involves UDP-glucose as the active form of glucose and requires energy from ATP and UTP.
    • Glycogen synthesis is initiated by UDP-glucose, with glycogenin acting as a receptor for glucose residues when glycogen is depleted.
    • The rate-limiting step in glycogen synthesis is the glycogen synthase step, which forms α(1-4) glycosidic bonds.
    • Branching in glycogen occurs after at least 11 glucose units and is catalyzed by the branching enzyme.
    • Glycogen breakdown involves glycogen phosphorylase breaking α-1,4 glycoside bonds, leading to the release of glucose-1-phosphate.

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    Glycogen Metabolism PDF

    Description

    Test your knowledge of glycogen metabolism with this quiz. Explore key concepts such as glycogenolysis, glycogen synthesis, sugar nucleotides, and the enzymes involved in glycogen breakdown and synthesis.

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