Glycolysis in Muscle Cells and Red Blood Cells
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Questions and Answers

What is the primary function of lactate dehydrogenase in muscle cells?

  • To regenerate NAD+ from NADH
  • To convert glucose to glycogen
  • To convert lactate to pyruvate
  • To convert pyruvate to lactate (correct)

    • What is the net gain of ATP in the conversion of glucose to pyruvate in the glycolysis pathway?

  • 2 ATP (correct)
  • 6 ATP
  • 8 ATP
  • 4 ATP

    • Which of the following statements is true about glycolysis in red blood cells?

  • It is the only source of energy for red blood cells (correct)
  • It is a reversible process
  • It is stimulated by high levels of insulin
  • It is inhibited by high levels of ATP

    • What is the purpose of substrate-level phosphorylation in glycolysis?

    <p>To generate ATP from ADP</p> Signup and view all the answers

    What is the role of NAD+ in the glycolysis pathway?

    <p>To act as a coenzyme in the conversion of glucose to pyruvate</p> Signup and view all the answers

    What is the purpose of controlling glycolysis in different tissues?

    <p>To regulate the amount of ATP produced</p> Signup and view all the answers

    Under which conditions is the Warburg Effect most beneficial to cancer cells?

    <p>Under low oxygen tension</p> Signup and view all the answers

    Which of the following is NOT a cell type where the glycolysis pathway is of particular importance?

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

    What is the net result of anaerobic glycolysis in terms of ATP production?

    <p>A net gain of 2 ATP molecules</p> Signup and view all the answers

    Which enzyme catalyzes the reaction that produces pyruvate in the glycolysis pathway?

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

    What is the primary difference between aerobic and anaerobic glycolysis?

    <p>The presence or absence of oxygen</p> Signup and view all the answers

    Which of the following statements is true about glycolysis in cancer cells?

    <p>It is inhibited by the presence of oxygen</p> Signup and view all the answers

    What is the downstream fate of pyruvate in anaerobic glycolysis?

    <p>It is converted to lactate</p> Signup and view all the answers

    What is the purpose of substrate-level phosphorylation in glycolysis?

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

    What is the primary source of glucose for glycolysis?

    <p>Sugars and starch from diet</p> Signup and view all the answers

    Which enzyme is inhibited by ATP in glycolysis?

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

    What is the product of the oxidation step in glycolysis?

    <p>1,3-Bisphosphoglycerate</p> Signup and view all the answers

    Which of the following tissues preferentially generates energy through anaerobic glycolysis?

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

    What is the result of substrate-level phosphorylation in glycolysis?

    <p>The production of 2 ATP</p> Signup and view all the answers

    What is the function of glyceraldehyde-3-phosphate dehydrogenase in glycolysis?

    <p>To convert glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate</p> Signup and view all the answers

    What is the result of the conversion of pyruvate to lactate in anaerobic glycolysis?

    <p>The regeneration of NAD+ from NADH</p> Signup and view all the answers

    Which of the following is NOT a product of the glycolytic pathway?

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

    What is the net yield of ATP from the conversion of glucose to pyruvate in glycolysis?

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

    Which enzyme catalyzes the conversion of glucose to glucose-6-phosphate in glycolysis?

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

    Study Notes

    Anaerobic Metabolism: Glycolysis

    Structure and Function of Glucose and Glycogen

    • Glucose: a monosaccharide, approximately 10g in plasma, osmotically active, immediate energy source through glycolysis
    • Glycogen: a polysaccharide, approximately 400g in tissue stores, low osmolarity, medium-term fuel source, synthesized and broken down in the liver

    Glycolysis: Key Points

    • Definition: conversion of glucose to pyruvate
    • Location: cytosol, involving 10 soluble enzymes
    • Tissues: all tissues
    • Functions: energy trapping (ATP synthesis), intermediates for fat synthesis, intermediates for amino acid synthesis

    Sources of Glucose for Glycolysis

    • Sugars and starch from diet
    • Breakdown of stored glycogen from the liver
    • Recycled glucose (from lactic acid, amino acids, or glycerol)

    The Glycolysis Pathway

    • A 10-reaction pathway converting glucose to pyruvate
    • Divided into 4 stages: activation, splitting, oxidation, and ATP synthesis

    Activation Stage of Glycolysis

    • Reaction 1: hexokinase or glucokinase converts glucose to glucose 6-phosphate, using ATP
    • Reaction 2: phosphohexose isomerase converts glucose 6-phosphate to fructose 6-phosphate
    • Reaction 3: phosphofructokinase converts fructose 6-phosphate to fructose 1,6-bisphosphate, using ATP

    Splitting of 6C Sugar to 3C Units

    • Reaction 4 and 5: aldolase and triose phosphate isomerase convert fructose 1,6-bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate

    Oxidation Step

    • Reaction 6: glyceraldehyde 3-phosphate dehydrogenase converts glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate, reducing NAD+ to NADH

    ATP Synthesis Stages

    • Reaction 7: phosphoglycerate kinase converts 1,3-bisphosphoglycerate to 3-phosphoglycerate, producing ATP
    • Reaction 8: phosphoglycerate mutase converts 3-phosphoglycerate to 2-phosphoglycerate
    • Reaction 9: enolase converts 2-phosphoglycerate to phosphoenolpyruvate
    • Reaction 10: pyruvate kinase converts phosphoenolpyruvate to pyruvate, producing ATP

    Yields of ATP from Glycolysis

    • Early stages use 2 ATP
    • Later stages produce 4 ATP
    • Net yield: 2 ATP (plus further ATP from mitochondrial metabolism)

    Anaerobic Glycolysis

    • Occurs when oxygen supplies are limited, converting pyruvate to lactate to regenerate NAD+
    • Important in red blood cells, skeletal muscle, and cancer cells

    Regulation of Glycolysis

    • Under allosteric control and hormonal control
    • One example of allosteric control is the inhibition of phosphofructokinase by ATP and citrate

    Specialized Functions in Tissues

    • Skeletal muscle: ATP production during intense exercise
    • Red blood cells: only pathway for ATP production, no mitochondria
    • Brain: major source of ATP, cannot use fats as fuels

    The Warburg Effect

    • Tumor cells preferentially generate energy through anaerobic glycolysis, producing lactate at a high rate even when mitochondria are intact

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    Description

    Quiz about glycolysis in muscle cells and red blood cells, covering topics such as lactate dehydrogenase, ATP gain, substrate-level phosphorylation, and NAD+ role.

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