Regulation of Enzymes in Glycolysis and Gluconeogenesis
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Questions and Answers

Which term is used to describe the dynamic steady state of a living cell?

  • Isotonic state
  • Eutrophic state
  • Homeorhesis
  • Homeostasis (correct)
  • What happens when the concentration of AMP in a cell is much lower compared to ATP and ADP?

  • AMP production is favored upon ATP depletion (correct)
  • The cell's energetic state is stabilized
  • AMP-dependent kinases are inhibited
  • ATP production is prioritized over AMP
  • What role does AMP-dependent kinase (AMPK) play in response to changes in a cell's energetic state?

  • Stabilizes ATP levels
  • Inhibits protein phosphorylation
  • Activates glycogen synthase
  • Promotes metabolic fluxes through multiple pathways (correct)
  • Why are steps 2 and 3 considered near equilibrium in a reaction according to the text?

    <p>Due to the similarity in forward and reverse rates</p> Signup and view all the answers

    What happens when glycogen synthase dissociates from the particle in glycogen metabolism?

    <p>Chain extension stops</p> Signup and view all the answers

    How does a change in external circumstances or energy supply impact the homeostasis of a living cell?

    <p>It triggers intrinsic regulatory mechanisms in pathways</p> Signup and view all the answers

    What is the relationship between high ATP concentrations and the rate of fructose 1,6-bisphosphate formation in glycolysis?

    <p>High ATP concentrations lead to low fructose 1,6-bisphosphate formation rate.</p> Signup and view all the answers

    What regulates the activation of Glycogen Synthase by dephosphorylating it?

    <p>Glucose 6-phosphate and glucose in surplus</p> Signup and view all the answers

    Which hormone inhibits the dephosphorylation of Glycogen Synthase by inactivating PP1?

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

    What causes the association of glycogen phosphorylase with other proteins, including PP1?

    <p>Glycogen targeting protein GM</p> Signup and view all the answers

    Which signaling pathway turns off GSK by phosphorylating it?

    <p>Glucagon (starvation signal)</p> Signup and view all the answers

    What stimulates the dephosphorylation of Glycogen Synthase during glucose surplus?

    <p>Glucose 6-phosphate and glucose itself</p> Signup and view all the answers

    What is the primary function of isozymes that catalyze the same reaction?

    <p>They provide redundancy and differential regulation.</p> Signup and view all the answers

    How does the sequestration of hexokinase IV by a nuclear binding protein affect enzyme activity?

    <p>It decreases hexokinase IV activity when glucose concentration is high.</p> Signup and view all the answers

    What effect does a high ATP concentration have on PFK activity?

    <p>Decreases the K0.5 value for fructose 6-phosphate binding.</p> Signup and view all the answers

    Why is it important to regulate hexokinase IV and not operate it simultaneously with other hexokinases?

    <p>To prevent futile energy loss.</p> Signup and view all the answers

    What is the primary difference between metabolic regulation and metabolic control?

    <p>Regulation maintains homeostasis, while control responds to external signals.</p> Signup and view all the answers

    What role does isozyme regulation play in metabolic pathways?

    <p>It controls the direction and speed of metabolic flux.</p> Signup and view all the answers

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