Clinical Biochemistry Lecture: Enzymes III and IV
24 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the effect of increasing substrate concentration on enzyme activity?

  • The velocity of the reaction increases, but then reaches a plateau (correct)
  • The velocity of the reaction decreases
  • The velocity of the reaction is unaffected by substrate concentration
  • The velocity of the reaction remains unchanged

    • What is Km?

  • The substrate concentration at half-maximal velocity (correct)
  • The rate of a reaction
  • The enzyme concentration required for maximum velocity
  • The maximum velocity of an enzyme

    • What happens to Vmax when enzyme concentration is doubled?

  • It is unaffected
  • It is halved
  • It remains the same
  • It is doubled (correct)

    • What is the relationship between enzyme concentration and the rate of a reaction?

    <p>The rate of a reaction is directly proportional to the enzyme concentration</p> Signup and view all the answers

    What is the shape of the reaction curve at relatively low concentrations of substrate?

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

    What is the effect of increasing enzyme concentration on Km?

    <p>Km remains the same</p> Signup and view all the answers

    What type of kinetics is observed when there is a small increase in V0 with increasing [S]?

    <p>Zero-order kinetics</p> Signup and view all the answers

    What is the significance of Km?

    <p>It is a constant for an enzyme, independent of enzyme concentration</p> Signup and view all the answers

    What happens to the velocity of an enzyme reaction when the temperature of the medium is increased?

    <p>It increases, reaches a maximum, and then falls</p> Signup and view all the answers

    What is the usual optimum pH range for most human enzymes?

    <p>Between 6 and 8</p> Signup and view all the answers

    What happens to the activity of an enzyme when the temperature is more than 50°C?

    <p>It decreases due to heat denaturation</p> Signup and view all the answers

    What is the term for the temperature at which the maximum amount of substrate is converted to product per unit time?

    <p>Optimum temperature</p> Signup and view all the answers

    What happens to the reaction rate in a reversible reaction when the product concentration is increased?

    <p>It slows down, stops, or even reverses</p> Signup and view all the answers

    What happens to the velocity of an enzyme reaction when the concentration of enzyme is increased, provided substrate concentration is unlimited?

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

    What is the term for the process by which the tertiary structure of protein is lost due to high temperature?

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

    What is the effect of pH on the net charge of amino acid residues at the active site?

    <p>It influences the net charge</p> Signup and view all the answers

    What is the result of an enzyme being activated by certain inorganic ions?

    <p>Increased activity</p> Signup and view all the answers

    What is the effect of a competitive inhibitor on the Km of an enzyme?

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

    What is the difference between a competitive and non-competitive inhibitor?

    <p>Competitive inhibitors bind to the active site, while non-competitive inhibitors bind to a different domain</p> Signup and view all the answers

    What is the effect of an increase in substrate concentration on competitive inhibition?

    <p>It relieves the inhibition</p> Signup and view all the answers

    What is the effect of a non-competitive inhibitor on the Vmax of an enzyme?

    <p>It decreases Vmax</p> Signup and view all the answers

    What is the mechanism of action of sulfonamide drugs?

    <p>They inhibit folic acid synthesis by competitive inhibition</p> Signup and view all the answers

    What is the result of converting an inactive pro-enzyme or zymogen to the active enzyme?

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

    What is the effect of a non-competitive inhibitor on the Km of an enzyme?

    <p>It has no effect on Km</p> Signup and view all the answers

    Study Notes

    Factors Affecting Enzyme Activity

    • Substrate concentration:
      • Velocity of reaction increases with increasing substrate concentration, initially in a linear relationship, then becoming hyperbolic
      • Km (Michaelis constant) is the substrate concentration at half-maximal velocity, representing 50% of enzyme molecules bound to substrate
      • Km is independent of enzyme concentration and remains constant for an enzyme
    • Enzyme concentration:
      • Velocity of reaction increases proportionally with enzyme concentration when sufficient substrate is present
    • Temperature:
      • Velocity of reaction increases with temperature, reaching a maximum (optimum temperature) and then decreasing
      • Most human enzymes have an optimum temperature around 37°C
    • pH:
      • Each enzyme has an optimum pH, with velocity drastically reduced on either side of the optimum
      • pH affects the charge on amino acid residues at the active site, influencing substrate binding and catalytic activity
    • Concentration of products:
      • In reversible reactions, increased product concentration slows down the reaction rate
    • Enzyme activation:
      • Certain inorganic ions (e.g., chloride and calcium) can activate enzymes

    Enzyme Inhibition

    • Competitive inhibition:
      • Inhibitor molecules compete with substrate molecules for the active site, reducing available enzyme molecules
      • Reversible, with excess substrate abolishing the inhibition
      • Increases Km for the substrate, but does not affect Vmax
    • Non-competitive inhibition:
      • Inhibitor binds to a different domain on the enzyme, reducing enzyme activity
      • Irreversible, with no competition between substrate and inhibitor
      • Does not affect Km, but decreases Vmax

    Pharmacological Applications

    • Competitive inhibitors can be used as pharmacological agents, such as sulfonamides, which inhibit folic acid synthesis in bacteria by competing with PABA

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    This quiz covers the factors affecting enzyme activity and other related concepts from Clinical Biochemistry lectures 10 and 11, as taught by Dr. Naeem Salih Alzaidi.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser