Lecture 18
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Questions and Answers

What is the major fate of glucose in animal tissues?

  • Direct excretion through the kidneys
  • Conversion into fats stored in adipose tissue
  • Breakdown in the glycolysis pathway followed by oxidation in the citric acid cycle (correct)
  • Conversion into glycogen stored mainly in the liver and muscle

    • By what means is glycogen stored in vertebrates and starch stored in plants?

  • Lipid droplets
  • Gaseous form
  • Intracellular vesicles
  • Polymeric storage form (correct)

    • How is glycogen regulated allosterically and hormonally in vertebrates?

  • By cortisol and adrenaline
  • By growth hormone and estrogen
  • By testosterone and progesterone
  • By insulin and glucagon (correct)

    • Where is glycogen primarily stored in the body?

    <p>In the liver and muscle</p> Signup and view all the answers

    Which product is excess glucose mainly converted into in the diet?

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

    What are cytosolic granules mainly composed of in terms of storage?

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

    What is the basic structure of amylopectin?

    <p>Branched structure with (α1→4) linkages</p> Signup and view all the answers

    Which polysaccharide has more branching than amylopectin?

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

    What is the product obtained by removing a glucose residue from the non-reducing end of a glycogen chain?

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

    Which enzyme is responsible for breaking down glycogen in muscle and liver?

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

    What is the function of liver glycogen?

    <p>Serve as a reservoir of glucose for other tissues</p> Signup and view all the answers

    Why is glycogen important for neurons of the brain and red blood cells?

    <p>It serves as a reservoir of glucose</p> Signup and view all the answers

    Why is the oxidation of the anomeric carbon C1 of glucose significant?

    <p>Basis for the Fehling's reaction</p> Signup and view all the answers

    What is the role of glycogen in vigorously contracting muscle?

    <p>Provide a quick source of energy</p> Signup and view all the answers

    Why can't C-1 of glucose be oxidized by Cu2+ in its ring form?

    <p>Is in equilibrium with the open-chain form</p> Signup and view all the answers

    What is the primary function of the liver in relation to glucose metabolism, compared to muscle?

    <p>The liver releases glucose into the bloodstream to supply other tissues, while muscle uses glucose for its own energy needs.</p> Signup and view all the answers

    What is the role of the glucose 6-phosphate transporter (T1) in the liver?

    <p>T1 transports glucose 6-phosphate from the cytosol to the lumen of the ER, where it can be hydrolyzed by glucose 6-phosphatase.</p> Signup and view all the answers

    What is the role of the glucose and phosphate transporters (T2 and T3) in the liver?

    <p>T2 and T3 transport glucose and phosphate, respectively, from the lumen of the ER to the cytosol.</p> Signup and view all the answers

    What is the purpose of the dephosphorylation of glucose 6-phosphate in the liver?

    <p>To release glucose into the bloodstream for use by other tissues.</p> Signup and view all the answers

    Where is the catalytic site of glucose 6-phosphatase located in the liver?

    <p>In the lumen of the endoplasmic reticulum (ER).</p> Signup and view all the answers

    Which enzyme is responsible for initiating glycogen synthesis?

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

    Which of the following is the activated form of glucose used as a substrate for glycogen synthase?

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

    Which of the following statements about muscle and adipose tissue is true?

    <p>They lack glucose 6-phosphatase, preventing gluconeogenesis.</p> Signup and view all the answers

    What is the role of the nucleoside triphosphate (NTP) in the formation of a sugar nucleotide?

    <p>It donates the phosphate group to the sugar phosphate.</p> Signup and view all the answers

    Which of the following statements about glycogen synthesis is true?

    <p>It involves the polymerization of hexoses using sugar nucleotides as intermediates.</p> Signup and view all the answers

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