Glucose Metabolism in Red Blood Cells
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Questions and Answers

What role does 2,3-bisphosphoglycerate play in relation to hemoglobin?

  • It is crucial for the release of O2 from hemoglobin. (correct)
  • It increases the production of ATP during glycolysis.
  • It is involved in the phosphorylation of glucose.
  • It regulates the conversion of pyruvate to lactate.

    • What is the consequence of arsenate poisoning on ATP production in glycolysis?

  • It enhances the overall glycolytic pathway efficiency.
  • It promotes the conversion of pyruvate to ATP.
  • It increases ATP yield through enhanced enzyme activity.
  • It bypasses step 7, leading to no net yield of ATP. (correct)

    • What is the primary role of insulin in glucose transport?

  • It decreases the number of GLUT 4 receptors.
  • It promotes rapid uptake of glucose by increasing GLUT 4 receptors. (correct)
  • It converts glucose to glucose-6-phosphate.
  • It inhibits glucose transporters.

    • Which enzyme is inhibited by glucose-6-phosphate?

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

    Which glucose transporter is primarily found in liver cells?

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

    What is the function of the enzyme 2,3-bisphosphoglycerate phosphatase?

    <p>It converts 2,3-BPG to 3-phosphoglycerate.</p> Signup and view all the answers

    Which of the following factors activates phosphofructokinase (PFK)?

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

    What happens when fructose-6-phosphate is present in high amounts?

    <p>It is converted to fructose-2,6-bisphosphate.</p> Signup and view all the answers

    In which type of cells are Na+-dependent co-transporters responsible for glucose transport located?

    <p>Intestinal and kidney cells</p> Signup and view all the answers

    What inhibits pyruvate kinase?

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

    What is the role of GLUT 4 in glucose regulation?

    <p>Facilitate glucose uptake in skeletal muscle and adipose tissues.</p> Signup and view all the answers

    What is produced when arseno-3-phosphoglycerate is hydrolyzed?

    <p>3-phosphoglycerate</p> Signup and view all the answers

    Which enzyme converts fructose-6-phosphate to fructose-2,6-bisphosphate?

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

    Which GLUT transporters are present in nearly all mammalian cells?

    <p>GLUT 1 and GLUT 3</p> Signup and view all the answers

    What is the effect of high levels of ATP on phosphofructokinase (PFK)?

    <p>It inhibits PFK.</p> Signup and view all the answers

    What happens to ATP production when step 7 of glycolysis is bypassed?

    <p>There is no net yield of ATP.</p> Signup and view all the answers

    Which of the following statements about GLUT transporters is true?

    <p>GLUT 7 transports glucose-6-phosphate to the ER.</p> Signup and view all the answers

    How does the transport of glucose occur via SGLT1?

    <p>It operates through secondary active transport mechanisms.</p> Signup and view all the answers

    Which of the following is a function of fructose-2,6-bisphosphate in glycolysis regulation?

    <p>It activates pyruvate kinase.</p> Signup and view all the answers

    What does the presence of citrate indicate in the context of phosphofructokinase activity?

    <p>It indicates a high-energy state.</p> Signup and view all the answers

    What is the primary method by which red blood cells generate adenosine triphosphate (ATP)?

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

    Approximately what percentage of glucose in red blood cells is used to produce 2,3-bisphosphoglycerate (2,3-BPG)?

    <p>25%</p> Signup and view all the answers

    What is the function of 2,3-bisphosphoglycerate (2,3-BPG) in red blood cells?

    <p>Decrease oxygen affinity of hemoglobin</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of 1,3-bisphosphoglycerate to 2,3-bisphosphoglycerate in red blood cells?

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

    How does red blood cells utilize the oxidative branch of the pentose phosphate pathway (PPP)?

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

    What role does glutathione play in red blood cells?

    <p>Oxidative stress defense</p> Signup and view all the answers

    What is the overall significance of glycolysis in red blood cells?

    <p>It is the primary pathway for ATP production.</p> Signup and view all the answers

    Which compound produced in glycolysis interacts with hemoglobin to modulate oxygen affinity?

    <p>2,3-bisphosphoglycerate</p> Signup and view all the answers

    What type of stress do red blood cells counteract using NADPH generated from the pentose phosphate pathway?

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

    What is the chemical structure interaction of 2,3-bisphosphoglycerate with hemoglobin?

    <p>It regulates the release of oxygen.</p> Signup and view all the answers

    Study Notes

    Glucose Metabolism in Red Blood Cells (RBCs)

    • RBCs exclusively utilize glycolysis for ATP production.
    • About 25% of glucose metabolized results in the synthesis of 2,3-bisphosphoglycerate (2,3-BPG), crucial for modulating hemoglobin's affinity for oxygen.
    • The pentose phosphate pathway (PPP) provides NADPH, essential for maintaining glutathione levels and combatting oxidative stress.

    Importance of Glycolysis in RBCs

    • 2,3-BPG acts as an allosteric effector that promotes oxygen release from hemoglobin.
    • Bisphosphoglycerate mutase catalyzes the conversion of 1,3-bisphosphoglycerate (1,3-BPG) to 2,3-BPG.
    • 2,3-BPG can be reversed to 3-phosphoglycerate, re-entering the glycolysis, consequently bypassing ATP production at step 7 while regulating oxygen release.

    Arsenate Poisoning Effects

    • Arsenate, a phosphorous analogue, replaces phosphate in 1,3-BPG, forming arseno-3-phosphoglycerate.
    • This compound hydrolyzes rapidly to 3-phosphoglycerate, leading to the bypassing of the glycolytic ATP-generating step.
    • Resulting in no net yield of ATP, which affects energy supply.

    Regulation of Glycolysis

    • Glucose transport into cells is the initial regulatory step, facilitated by specific transporters (e.g., GLUT family).
    • SGLT1 transports glucose via Na+-dependent co-transport in intestine and kidney cells.
    • GLUT 1 & GLUT 3 transport glucose across almost all mammalian cells, GLUT 2 is present in the liver, GLUT 4 is found in muscle and adipose tissue and is regulated by insulin, while GLUT 5 and GLUT 7 have specific functions in glucose and glucose-6-phosphate transport.

    Key Enzymatic Regulators

    • Hexokinase: Inhibited by glucose-6-phosphate; initiates glycolysis by converting glucose to glucose-6-phosphate.
    • Phosphofructokinase (PFK):
      • Inhibited by elevated ATP and citrate levels.
      • Activated by AMP and fructose-2,6-bisphosphate, signaling a need for glycolysis based on substrate availability.
    • Pyruvate Kinase:
      • Inhibited by ATP, indicating sufficient energy availability.
      • Activated by fructose-2,6-bisphosphate, enhancing glycolytic throughput.

    Additional Points on PFK Regulation

    • High fructose-6-phosphate levels are converted to fructose-2,6-bisphosphate through Phosphofructokinase-2 (PFK-2), promoting glycolysis.
    • Presence of fructose-2,6-bisphosphate enhances the glycolytic pathway, while FBPase-2 acts as a counter regulator, influencing the fructose-2,6-bisphosphate levels.

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    Related Documents

    Glycolysis and Regulation PDF

    Description

    This quiz focuses on the metabolic pathways utilized by red blood cells, particularly glycolysis and the pentose phosphate pathway. Learn about the synthesis of 2,3-bisphosphoglycerate and its role in oxygen release. Additionally, explore the effects of arsenate poisoning on glucose metabolism in RBCs.

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