Hexose Monophosphate Shunt Pathway Quiz
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Questions and Answers

What is the main aim of the uronic acid pathway?

  • Production of glucose
  • Synthesis of glucuronic acid (correct)
  • Conversion to uridine triphosphate
  • Generation of free radicals

    • Which form of glucose is produced in the uronic acid pathway?

  • Glucuronic acid
  • Fructose 6-phosphate
  • Glucose 6-phosphate
  • UDP-glucose (correct)

    • What is the end product of glucuronic acid metabolism in humans?

  • Glyceraldehyde 3-phosphate
  • D-xylulose 5-phosphate (correct)
  • Fructose 1,6-bisphosphate
  • Glucose 6-phosphate

    • How does glucuronic acid contribute to detoxification?

    <p>By conjugating with agents for excretion</p> Signup and view all the answers

    Why is bilirubin mentioned in relation to the importance of the uronic acid pathway?

    <p>To facilitate the excretion and prevent jaundice</p> Signup and view all the answers

    What is the main role of the Cytochrome P450 mono-oxygenase system in the human body?

    <p>Detoxifying harmful agents like drugs and food preservatives</p> Signup and view all the answers

    In the Cytochrome P450 monooxygenase system, what provides the reducing equivalents (hydrogen) required for the series of reactions?

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

    Which enzyme deficiency is characterized by hemolytic anemia due to the inability to detoxify oxidizing agents?

    <p>G6PD deficiency</p> Signup and view all the answers

    Aside from hemolytic anemia, what is another clinical manifestation of G6PD deficiency that typically appears 1–4 days after birth?

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

    What resistance effect does G6PD deficiency share with Sickle cell trait and thalassemias?

    <p>Resistance to malaria</p> Signup and view all the answers

    Which pathway is a parallel pathway to glycolysis and converts glucose 6-phosphate to fructose 6-phosphate and glyceraldehyde 3-phosphate?

    <p>Hexose monophosphate shunt</p> Signup and view all the answers

    What is the primary product generated from the conversion of glucose 6-phosphate in the Hexose monophosphate shunt?

    <p>Ribose 5-phosphate</p> Signup and view all the answers

    Which molecule is crucial for maintaining the integrity of the red blood cell membrane?

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

    Which metabolic pathway is essential for detoxifying bilirubin released during hemoglobin breakdown?

    <p>Glucuronic acid pathway</p> Signup and view all the answers

    What is the main function of the Hexose monophosphate shunt in the context of red blood cells?

    <p>Generation of NADPH</p> Signup and view all the answers

    What is the role of glutathione peroxidase in the detoxification process?

    <p>It reduces H2O2 to water in the presence of reduced glutathione.</p> Signup and view all the answers

    What is the function of NADPH in the detoxification process related to hydrogen peroxide?

    <p>It regenerates GSH through a reaction catalyzed by glutathione reductase.</p> Signup and view all the answers

    Which enzyme plays a crucial role in defending the body against hydrogen peroxide?

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

    What is the primary function of reduced glutathione (GSH) in the detoxification process?

    <p>To detoxify hydrogen peroxide</p> Signup and view all the answers

    How does the cell regenerate GSH after it has reacted with hydrogen peroxide?

    <p>Via a reaction catalyzed by glutathione reductase using NADPH</p> Signup and view all the answers

    Which process requires GSH for the protection of cell membranes from free radicals and peroxides within the cell?

    <p>Oxidation to UDP-glucuronic acid</p> Signup and view all the answers

    What is the consequence of oxidation of sulfhydryl groups in proteins, including hemoglobin?

    <p>Formation of denatured proteins</p> Signup and view all the answers

    Which factor is crucial for maintaining RBC deformability and preventing their removal by macrophages?

    <p>RBC membrane rigidity</p> Signup and view all the answers

    In G6PD deficiency, which pathway provides the primary means of generating NADPH in RBCs?

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

    What precipitating factor in G6PD deficiency leads to hemolytic anemia upon exposure?

    <p>Antibiotics like sulfamethoxazole</p> Signup and view all the answers

    What is the role of Glucose 6-phosphate dehydrogenase (G6PD) in the Hexose monophosphate shunt pathway?

    <p>It initiates the pathway and is the rate-limiting step.</p> Signup and view all the answers

    How does NADPH regulate G6PD activity in the Hexose monophosphate shunt pathway?

    <p>Directly inhibits G6PD activity.</p> Signup and view all the answers

    What is the significance of the NADPH/NADP+ ratio in the Hexose monophosphate shunt pathway?

    <p>It ensures production of only the required amount of NADPH.</p> Signup and view all the answers

    What role does Insulin play in the Hexose monophosphate shunt pathway?

    <p>Upregulates G6PD gene expression.</p> Signup and view all the answers

    Which product of the Hexose monophosphate shunt pathway is essential for the synthesis of nucleotides?

    <p>Ribose-5-P</p> Signup and view all the answers

    What is the role of NADPH oxidase in white blood cells in the context of the text?

    <p>Reducing O2 to superoxide anion for killing bacterial cells</p> Signup and view all the answers

    Which enzyme catalyzes the synthesis of nitric oxide as described in the text?

    <p>Nitric oxide synthase</p> Signup and view all the answers

    What happens to nitric oxide (NO) due to its reaction with O2 as described in the text?

    <p>It converts into nitrates and nitrites</p> Signup and view all the answers

    Which molecule has a very short half-life in tissues due to its reactivity with oxygen?

    <p>Nitric oxide (NO)</p> Signup and view all the answers

    What is the endogenous antioxidant enzyme responsible for removing superoxide anion after bacterial cell killing?

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

    What substrates are required for the synthesis of nitric oxide according to the text?

    <p>Arginine, O2, and NADPH</p> Signup and view all the answers

    Study Notes

    Uronic Acid Pathway

    • The main aim of the uronic acid pathway is to detoxify bilirubin released during hemoglobin breakdown.
    • Glucuronic acid is produced in the uronic acid pathway.
    • The end product of glucuronic acid metabolism in humans is the detoxification of bilirubin.

    Glucuronic Acid and Detoxification

    • Glucuronic acid contributes to detoxification by conjugating with bilirubin, making it water-soluble and excretable.

    Cytochrome P450 Mono-Oxygenase System

    • The Cytochrome P450 mono-oxygenase system is responsible for detoxifying xenobiotics and metabolizing certain drugs in the human body.
    • NADPH provides the reducing equivalents (hydrogen) required for the series of reactions in the Cytochrome P450 mono-oxygenase system.

    G6PD Deficiency

    • Glucose-6-phosphate dehydrogenase (G6PD) deficiency is characterized by hemolytic anemia due to the inability to detoxify oxidizing agents.
    • Neonatal jaundice typically appears 1–4 days after birth in individuals with G6PD deficiency.
    • G6PD deficiency shares a resistance effect with Sickle cell trait and thalassemias, providing protection against malaria.

    Hexose Monophosphate Shunt

    • The Hexose monophosphate shunt is a parallel pathway to glycolysis, converting glucose 6-phosphate to fructose 6-phosphate and glyceraldehyde 3-phosphate.
    • The primary product generated from the conversion of glucose 6-phosphate in the Hexose monophosphate shunt is NADPH.
    • NADPH is crucial for maintaining the integrity of the red blood cell membrane.
    • The main function of the Hexose monophosphate shunt in the context of red blood cells is to generate NADPH for detoxification.

    Glutathione and Detoxification

    • Glutathione peroxidase plays a crucial role in defending the body against hydrogen peroxide.
    • NADPH reduces oxidized glutathione (GSSG) back to reduced glutathione (GSH) after it reacts with hydrogen peroxide.
    • GSH is essential for protecting cell membranes from free radicals and peroxides within the cell.
    • The oxidation of sulfhydryl groups in proteins, including hemoglobin, can lead to the formation of denatured proteins.

    G6PD Deficiency and RBCs

    • In G6PD deficiency, the Pentose phosphate pathway provides the primary means of generating NADPH in RBCs.
    • Oxidative stress, such as that caused by certain medications, can precipitate hemolytic anemia in individuals with G6PD deficiency.
    • G6PD plays a crucial role in regulating the NADPH/NADP+ ratio in the Hexose monophosphate shunt pathway.

    Insulin and Nitric Oxide

    • Insulin has no role in the Hexose monophosphate shunt pathway.
    • Nitric oxide synthase catalyzes the synthesis of nitric oxide.
    • Nitric oxide (NO) reacts with O2 to form nitrate and nitrite.
    • Nitric oxide has a very short half-life in tissues due to its reactivity with oxygen.
    • Superoxide dismutase is the endogenous antioxidant enzyme responsible for removing superoxide anion after bacterial cell killing.
    • The substrates required for the synthesis of nitric oxide are L-arginine, oxygen, and NADPH.

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    Related Documents

    L8 - Metabolic Pathways in RBCs PDF

    Description

    Test your knowledge on the irreversible oxidative phase and reversible sugar-phosphate interconversions in the Hexose Monophosphate Shunt pathway. Explore the regulation of the pathway, focusing on the role of Glucose 6-phosphate dehydrogenase (G6PD) and its feedback inhibition by NADPH.

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