Factors Affecting Enzyme Action
44 Questions
3 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 occurs when all enzyme binding sites are saturated with substrate?

  • The maximum velocity (Vmax) is reached (correct)
  • The substrate concentration has no effect
  • The reaction rate decreases
  • The enzyme concentration increases

    • What happens to the reaction rate as substrate concentration increases, assuming enzyme concentration remains constant?

  • The reaction rate decreases after a point
  • The reaction rate is independent of substrate concentration
  • The reaction rate initially increases and then levels off (correct)
  • The reaction rate remains the same

    • At what temperature do most enzymes exhibit peak activity in humans?

  • 50°C
  • 25°C
  • 37°C (correct)
  • 60°C

    • What is the effect of high temperatures on enzyme activity?

    <p>It causes denaturation and decreases the velocity (B)</p> Signup and view all the answers

    How does pH affect enzyme activity?

    <p>It affects the ionization of amino acids in the active site (C)</p> Signup and view all the answers

    What does the term Km represent in enzyme kinetics?

    <p>The substrate concentration at which the reaction rate is half of Vmax (C)</p> Signup and view all the answers

    Which of the following statements about substrate concentration and reaction rate is incorrect?

    <p>Reaction rate continues to rise beyond Vmax with increased substrate (C)</p> Signup and view all the answers

    What is the primary factor that causes variations in enzyme response to substrate concentration?

    <p>Enzyme structure (D)</p> Signup and view all the answers

    Why does enzyme activity show a hyperbolic dependence on substrate concentration?

    <p>As a result of all binding sites becoming occupied by substrate at high concentrations (A)</p> Signup and view all the answers

    What is the primary factor that determines enzyme specificity?

    <p>The 3-D shape and arrangement of functional groups (D)</p> Signup and view all the answers

    What happens to the initial velocity of an enzyme-catalyzed reaction when the amount of enzyme is increased?

    <p>It increases proportionally (B)</p> Signup and view all the answers

    What does enzyme kinetics primarily study?

    <p>The velocity of reactions catalyzed by enzymes (D)</p> Signup and view all the answers

    Which of the following factors is NOT affecting enzyme activity?

    <p>Color of the enzyme (C)</p> Signup and view all the answers

    How is the rate of reaction visually represented in enzyme kinetics?

    <p>As a hyperbolic curve (B)</p> Signup and view all the answers

    What may cause the decline in the rate of an enzyme-catalyzed reaction over time?

    <p>Denaturation of the enzyme (D)</p> Signup and view all the answers

    What is the initial velocity (Vi) of an enzyme-catalyzed reaction?

    <p>The initial portion of the reaction correlated with time (A)</p> Signup and view all the answers

    What is the measurement unit for the velocity of an enzyme-catalyzed reaction?

    <p>Micromoles per minute (B)</p> Signup and view all the answers

    Which type of interaction do enzymes primarily use to bind substrates?

    <p>Stabilized interactions based on charge and polarity (A)</p> Signup and view all the answers

    What may occur if a product of an enzyme-catalyzed reaction inhibits the enzyme?

    <p>It decreases the reaction rate (A)</p> Signup and view all the answers

    What is the effect of competitive inhibitors on Km?

    <p>Km is increased, requiring more substrate to reach Vmax (C)</p> Signup and view all the answers

    Which of the following correctly describes noncompetitive inhibition?

    <p>It binds to either the enzyme or the ES complex equally. (C)</p> Signup and view all the answers

    What is a potential consequence of noncompetitive inhibitors?

    <p>They decrease the Vmax without changing the Km. (D)</p> Signup and view all the answers

    What role does acetylcholinesterase play in the nervous system?

    <p>It hydrolyzes acetylcholine, regulating nerve signals. (A)</p> Signup and view all the answers

    How does penicillin exert its antibacterial effects?

    <p>By preventing the cross-linking of peptidoglycan in bacterial cell walls. (B)</p> Signup and view all the answers

    Which of the following statements regarding enzyme inhibitors is true?

    <p>Competitive inhibition can always be reversed by increasing substrate concentration. (B)</p> Signup and view all the answers

    What is a primary characteristic of enzymes?

    <p>They increase the rate of a reaction without being changed. (C)</p> Signup and view all the answers

    What describes the active site of an enzyme?

    <p>An area that binds substrates to form a complex. (A)</p> Signup and view all the answers

    Which model illustrates how an enzyme binds its substrate?

    <p>The lock-and-key model. (A), The induced-fit model. (B)</p> Signup and view all the answers

    What role do cofactors or coenzymes play in enzymatic reactions?

    <p>They assist enzyme activity. (D)</p> Signup and view all the answers

    Activation energy is defined as:

    <p>The energy required to start a reaction. (C)</p> Signup and view all the answers

    How do enzymes affect the activation energy of a reaction?

    <p>They decrease the activation energy needed. (C)</p> Signup and view all the answers

    What is a characteristic of the specificity of an enzyme?

    <p>It is correlated to the enzyme's active site structure. (D)</p> Signup and view all the answers

    What happens during the formation of an enzyme-substrate complex?

    <p>Weak interactions bind the substrate to the active site. (C)</p> Signup and view all the answers

    In what way do enzymes affect biochemical pathways?

    <p>They facilitate multiple steps within these pathways. (A)</p> Signup and view all the answers

    What type of interactions primarily bond the substrate to the active site of an enzyme?

    <p>Non-covalent bonds. (A)</p> Signup and view all the answers

    What does a low Km value indicate about an enzyme?

    <p>The enzyme has high affinity for the substrate. (B)</p> Signup and view all the answers

    In the context of enzyme kinetics, what does zero-order kinetics imply?

    <p>The rate of reaction is constant and independent of substrate concentration. (C)</p> Signup and view all the answers

    What does the Lineweaver-Burk plot allow researchers to determine directly?

    <p>The maximum rate of reaction (Vmax) and the Michaelis constant (Km). (C)</p> Signup and view all the answers

    What is true about competitive inhibitors?

    <p>They usually have structures similar to the substrate. (B)</p> Signup and view all the answers

    What happens to the initial velocity (Vo) of an enzyme-catalyzed reaction if the enzyme concentration is halved?

    <p>It decreases to half of its original value. (D)</p> Signup and view all the answers

    In enzyme kinetics, what does a high Km value indicate?

    <p>A higher substrate concentration is required for half saturation. (C)</p> Signup and view all the answers

    What characterizes irreversible enzyme inhibitors?

    <p>They bind covalently to the enzyme's active site. (C)</p> Signup and view all the answers

    Which part of the Lineweaver-Burk plot corresponds to Km?

    <p>X-intercept (B)</p> Signup and view all the answers

    What is the effect of increasing substrate concentration on a reaction inhibited by a competitive inhibitor?

    <p>It can reverse the inhibition and increase reaction rate. (D)</p> Signup and view all the answers

    Flashcards

    Enzyme

    A protein catalyst that speeds up chemical reactions without being consumed.

    Substrate

    The molecule an enzyme acts upon.

    Reaction Velocity

    The rate of product formation or substrate consumption.

    Vmax

    The maximum reaction rate, when all enzyme active sites are saturated.

    Signup and view all the flashcards

    Km

    The substrate concentration at which the reaction rate is half of Vmax.

    Signup and view all the flashcards

    Michaelis-Menten equation

    An equation describing the relationship between reaction velocity and substrate concentration for enzyme-catalyzed reactions.

    Signup and view all the flashcards

    Active site

    The region of an enzyme where the substrate binds.

    Signup and view all the flashcards

    Enzyme-substrate complex

    The temporary molecule formed when an enzyme binds to its substrate.

    Signup and view all the flashcards

    Competitive inhibitor

    A molecule that competes with the substrate for the active site.

    Signup and view all the flashcards

    Noncompetitive inhibitor

    A molecule that inhibits enzyme activity by binding to a site other than the active site.

    Signup and view all the flashcards

    Activation energy

    The energy needed for a chemical reaction to start.

    Signup and view all the flashcards

    Initial velocity

    The reaction rate measured at the beginning of a reaction.

    Signup and view all the flashcards

    Enzyme saturation

    The state where all enzyme active sites are occupied by substrate.

    Signup and view all the flashcards

    Cofactor

    A non-protein molecule required by some enzymes for catalytic activity.

    Signup and view all the flashcards

    Lineweaver-Burk plot

    A graph that transforms the Michaelis-Menten equation into a straight line.

    Signup and view all the flashcards

    Enzyme kinetics

    The study of the rates of enzyme-catalyzed reactions.

    Signup and view all the flashcards

    Temperature

    A factor affecting enzymatic activity.

    Signup and view all the flashcards

    pH

    A factor affecting enzymatic activity.

    Signup and view all the flashcards

    Reversible inhibitor

    Inhibitor affecting the rate of the reaction by a mechanism which is reversible.

    Signup and view all the flashcards

    Irreversible inhibitor

    Inhibitor inactivating an enzyme in a process that is permanent or at least long lasting.

    Signup and view all the flashcards

    Enzyme specificity

    The ability of enzyme to bind to certain substrates, not all.

    Signup and view all the flashcards

    Study Notes

    Concentration of Substrate and Reaction Rate

    • Initial velocity of a reaction is directly proportional to substrate concentration until reaching maximum velocity (Vmax).
    • Beyond Vmax, further substrate increases do not affect reaction velocity when enzyme concentration remains constant.
    • Reaction rate is the amount of substrate converted to product per unit time, commonly expressed as micromoles of product formed per minute.
    • Reaction rate increases with substrate concentration until all enzyme binding sites are saturated.

    Factors Affecting Enzyme Action

    • Enzyme responses vary with substrate concentration, temperature, and pH levels.
    • At low temperatures, enzyme activity is minimal; activity increases with temperature until an optimal peak is reached (typically around 37°C in humans).
    • High temperatures can lead to denaturation of enzymes, reducing reaction velocity.

    Enzyme Characteristics

    • Enzymes are catalysts that accelerate reaction rates without being consumed; they are proteins with high specificity.
    • They affect the rate of reaction but not the overall equilibrium.
    • Enzymes can require cofactors or coenzymes and participate in various biochemical pathways.

    Active Site and Mechanism of Action

    • The active site is the enzyme region that binds substrates, forming an enzyme-substrate complex through weak non-covalent interactions.
    • Activation energy is the energy needed for substrates to reach the transition state; enzymes lower this energy barrier.
    • Specificity of enzymes is determined by both substrate and enzyme functional groups and their spatial arrangement.

    Enzyme Kinetics

    • Enzyme kinetics studies reaction velocity, defined as the rate of product formation or substrate consumption over time.
    • Initial velocity (Vi) is measured during the first portion of the reaction, correlating product increase with time.
    • Factors affecting enzyme activity include enzyme concentration, with initial velocity proportionate to enzyme amount, independent of substrate concentration parameters such as Km.

    Michaelis-Menten Kinetics

    • The relation between reaction velocity (V) and substrate concentration ([S]) can be described by the Michaelis-Menten equation.
    • When [S] exceeds Km, the reaction rate reaches Vmax, indicating a zero-order reaction.
    • The Lineweaver-Burk Plot provides a linear transformation of the Michaelis-Menten equation, allowing easy determination of Vmax and Km from graph intercepts.

    Enzyme Inhibition

    • Enzyme inhibitors reduce reaction velocity and catalytic activity; can be reversible or irreversible.
    • Competitive inhibitors resemble substrate and compete for the active site, increasing the apparent Km but not affecting Vmax.
    • Noncompetitive inhibitors bind at a site separate from the substrate, reducing Vmax without affecting Km.

    Enzyme Inhibitors in Medicine

    • Sarin is a nerve gas that inhibits acetylcholinesterase, preventing acetylcholine hydrolysis, leading to excessive neuronal stimulation and severe physiological effects.
    • Penicillin acts as an antibiotic by inhibiting bacterial peptidoglycan synthesis, preventing cell wall formation and bacterial growth.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Enzyme Kinetics PDF

    Description

    This quiz explores the relationship between substrate concentration and enzyme activity. It focuses on how the initial velocity of a reaction depends on substrate amounts and the concept of maximum velocity (Vmax). Additionally, it addresses various factors that influence enzyme efficiency and response to substrate changes.

    More Like This

    Enzyme Kinetics and Substrate Concentration
    6 questions

    Enzyme Kinetics and Substrate Concentration

    TranquilCaesura avatar
    TranquilCaesura
    Enzyme Kinetics Part 2: Substrate Concentration
    25 questions

    Enzyme Kinetics Part 2: Substrate Concentration

    UnwaveringFable avatar
    UnwaveringFable
    Enzyme Kinetics and Km in Biochemistry
    18 questions

    Enzyme Kinetics and Km in Biochemistry

    ExultantDenouement avatar
    ExultantDenouement
    Enzyme Kinetics Overview
    49 questions

    Enzyme Kinetics Overview

    InfallibleBigBen avatar
    InfallibleBigBen
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser