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Glucose and Glycogen Regulation Practice 2 quiz

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  • At what concentration is fructose 2,6-bisphosphate effective in activating phosphofructokinase 1?
    Fructose 2,6-bisphosphate is effective at activating phosphofructokinase 1 at 1 micromolar concentration.
  • Where is glucokinase found in the body?
    Glucokinase is found only in the liver.
  • What is the primary role of the liver regarding glucose?
    The liver is responsible for blood glucose management and gluconeogenesis.
  • What happens to hexokinase activity when glucose 6-phosphate levels are high?
    Hexokinase is inhibited by glucose 6-phosphate, creating a negative feedback mechanism.
  • Does glucokinase get inhibited by glucose 6-phosphate?
    No, glucokinase continues to produce glucose 6-phosphate regardless of its concentration.
  • How does the Km of glucokinase compare to that of hexokinase?
    Glucokinase has a higher Km than hexokinase.
  • What does a higher Km for glucokinase mean in terms of reaction velocity?
    A higher Km allows glucokinase to work faster at higher glucose concentrations compared to hexokinase.
  • What determines the reaction rate of glucokinase in the liver?
    The supply of glucose determines the reaction rate of glucokinase.
  • What determines the reaction rate of hexokinase?
    The demand for glucose determines the reaction rate of hexokinase.
  • Why does the liver need to take in as much glucose as possible?
    The liver needs to take in as much glucose as possible to maintain blood sugar levels.
  • Which tissue has a higher Vmax for glycogen phosphorylase: muscle or liver?
    Muscle glycogen phosphorylase has a higher Vmax than liver glycogen phosphorylase.
  • Why does muscle glycogen phosphorylase have a higher Vmax?
    Muscles need to rapidly mobilize glycogen to support quick energy needs during intense activity.
  • Why does liver glycogen phosphorylase have a lower Vmax?
    The liver needs to maintain blood glucose levels more tightly regulated, so a lower Vmax helps control glucose release.
  • What is the main function of muscle glycogen phosphorylase during fight or flight situations?
    It mobilizes glycogen quickly to support rapid muscle contraction.
  • How does the liver regulate glucose release compared to muscle?
    The liver releases glucose more carefully and slowly, while muscle releases it rapidly for immediate energy.