Biochemistry LE 3: Integration of Carbohydrates and Lipids
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Questions and Answers

What is the primary way to control the rate of an enzyme?

  • Modifying the catalytic site of the enzyme
  • Increasing the concentration of the substrate
  • Changing the pH of the reaction
  • Changing the number of enzymes through gene expression (correct)

    • What is rapid control in enzymatic regulation?

  • Refers to the activity of enzymes due to covalent modification or allosteric regulation (correct)
  • Regulation of enzyme activity through substrate binding
  • Refers to the number of enzymes due to gene expression
  • Regulation of enzyme activity through allosteric regulation

    • What is the main factor that affects enzyme activity?

  • The concentration of the substrate
  • The pH of the reaction
  • The temperature of the reaction
  • The binding of a substrate or product within the catalytic site (correct)

    • What is the difference between slow control and rapid control?

    <p>Slow control refers to the number of enzymes, while rapid control refers to the activity of enzymes</p> Signup and view all the answers

    What is the primary target of slow control?

    <p>The number of enzymes</p> Signup and view all the answers

    What is the primary mechanism of rapid control?

    <p>Covalent modification or allosteric regulation</p> Signup and view all the answers

    What is the effect of substrate binding on enzyme activity?

    <p>It increases the enzyme activity</p> Signup and view all the answers

    What is the purpose of enzymatic regulation?

    <p>To maintain homeostasis in response to changes in the environment</p> Signup and view all the answers

    What is the relationship between enzymatic regulation and glucose homeostasis?

    <p>Enzymatic regulation is necessary for glucose homeostasis</p> Signup and view all the answers

    What type of modification is depicted in the regulation of PK through phosphorylation and dephosphorylation?

    <p>Reversible covalent modification</p> Signup and view all the answers

    What is the primary function of insulin in the well-fed state?

    <p>To activate phosphoprotein phosphatases</p> Signup and view all the answers

    What type of inhibitor is defined as a compound that decreases the velocity of the reaction by binding to the enzyme?

    <p>Reversible inhibitor</p> Signup and view all the answers

    What is the characteristic of a competitive inhibitor?

    <p>It is a close structural analog of the substrate</p> Signup and view all the answers

    What type of inhibition is depicted in the figure showing malonate with succinate dehydrogenase?

    <p>Competitive inhibition</p> Signup and view all the answers

    What is the term for the process of removing a phosphate group from a protein?

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

    What is the hormonal state during the well-fed state?

    <p>Predominantly insulin</p> Signup and view all the answers

    What is the term for the process of adding a phosphate group to a protein?

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

    What type of inhibitor binds to an allosteric site of the enzyme?

    <p>Non-competitive inhibitor</p> Signup and view all the answers

    What is the characteristic of Hexokinase in terms of Km and Vmax?

    <p>Low Km and low Vmax</p> Signup and view all the answers

    What is the effect of Fructose-6-Phosphate on glucokinase?

    <p>It facilitates the movement of glucokinase from the cytosol to the nucleus</p> Signup and view all the answers

    What is the activator of glucokinase?

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

    What is the effect of insulin on glycogen synthase?

    <p>It dephosphorylates glycogen synthase, activating it</p> Signup and view all the answers

    What type of regulation is involved in the modification of glycogen synthase?

    <p>Covalent modification</p> Signup and view all the answers

    What is the characteristic of Glucokinase in terms of Km and Vmax?

    <p>High Km and high Vmax</p> Signup and view all the answers

    What is the state of Pyruvate kinase during the well-fed state?

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

    What is the effect of glucose on glucokinase bound to regulatory proteins?

    <p>It stimulates the dissociation of glucokinase from regulatory proteins</p> Signup and view all the answers

    What is the difference between Hexokinase and Glucokinase in terms of genetic regulation?

    <p>Glucokinase is induced by insulin, while Hexokinase is not</p> Signup and view all the answers

    What is the result of a high-calorie diet on the gene for acetyl CoA carboxylase?

    <p>It increases the rate of transcription of the gene.</p> Signup and view all the answers

    What is the role of citrate in fatty acid synthesis?

    <p>It allosterically activates acetyl CoA carboxylase.</p> Signup and view all the answers

    What is the effect of a low-calorie diet on the gene for acetyl CoA carboxylase?

    <p>It reduces the rate of transcription of the gene.</p> Signup and view all the answers

    What is the ultimate product of fatty acid synthesis that inhibits the enzyme?

    <p>Palmitoyl CoA</p> Signup and view all the answers

    What activates the enzyme acetyl CoA carboxylase during fatty acid synthesis?

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

    What is the function of insulin in fatty acid synthesis?

    <p>It stimulates the phosphatase that dephosphorylates acetyl CoA carboxylase.</p> Signup and view all the answers

    What is the result of low energy levels on the enzyme acetyl CoA carboxylase?

    <p>It is phosphorylated and inactivated</p> Signup and view all the answers

    What is the role of palmitoyl CoA in fatty acid synthesis?

    <p>It inhibits acetyl CoA carboxylase</p> Signup and view all the answers

    What type of regulation is involved in the inactivation of acetyl CoA carboxylase during fasting?

    <p>All of the above</p> Signup and view all the answers

    What happens to the activity of HMG-CoA reductase when cholesterol and bile salts levels increase in cells?

    <p>It becomes more susceptible to ubiquitination and proteolysis</p> Signup and view all the answers

    What is the function of the sterol-sensing regions in HMG-CoA reductase?

    <p>To regulate the enzyme's activity</p> Signup and view all the answers

    What is the effect of insulin release on PFK-2 kinase?

    <p>It dephosphorylates the enzyme</p> Signup and view all the answers

    What is the effect of glucagon release on Pyruvate kinase?

    <p>It phosphorylates the enzyme</p> Signup and view all the answers

    What is the effect of insulin release on Glycogen synthase?

    <p>It dephosphorylates the enzyme</p> Signup and view all the answers

    What is the effect of glucagon release on Glycogen phosphorylase?

    <p>It phosphorylates the enzyme</p> Signup and view all the answers

    What is the effect of insulin release on Pyruvate dehydrogenase?

    <p>It dephosphorylates the enzyme</p> Signup and view all the answers

    What is the effect of glucagon release on Acetyl CoA carboxylase?

    <p>It phosphorylates the enzyme</p> Signup and view all the answers

    What is the net result of insulin release on liver metabolism?

    <p>Glycolysis and fatty acid synthesis</p> Signup and view all the answers

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