Chemical Equilibrium and Reaction Coupling
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Questions and Answers

What is the primary function of a catalyst in a reaction?

  • Increase the activation energy
  • Change the nature of the reaction
  • Consumed by the reaction
  • Decrease the activation energy (correct)

    • Which statement about enzymes is true?

  • Enzymes increase activation energy
  • Enzymes are not specific for the reactions they catalyze
  • Enzymes change the nature of a reaction
  • Enzymes do not change ΔG for a reaction (correct)

    • What holds the enzyme-substrate complex together?

  • Hydrogen bonds, electrical attraction, or hydrophobic interactions (correct)
  • Covalent bonds only
  • Ionic interactions only
  • Van der Waals forces

    • What happens to enzymes in a reaction?

    <p>Not consumed and can act repeatedly</p> Signup and view all the answers

    What is the function of the active site in an enzyme?

    <p>Specifically bind to a substrate like a lock and key</p> Signup and view all the answers

    Which is NOT a property of enzymes?

    <p>Change the nature of a reaction</p> Signup and view all the answers

    What is the role of enzymes regarding activation energy in reactions?

    <p>Lower activation energy barrier</p> Signup and view all the answers

    'Induced fit' refers to what process in enzyme-catalyzed reactions?

    <p>Enzymes changing shape upon substrate binding</p> Signup and view all the answers

    What is the main purpose of metabolic pathways?

    <p>To control the sequence of enzymatically-controlled reactions</p> Signup and view all the answers

    What is the role of the commitment step in a metabolic pathway?

    <p>It is the step that begins the sequence of reactions</p> Signup and view all the answers

    What is the purpose of feedback (negative) inhibition in a metabolic pathway?

    <p>To shut down the pathway when the final product is abundant</p> Signup and view all the answers

    What is the relationship between metabolic pathways and homeostasis?

    <p>Regulation of enzymes in metabolic pathways helps maintain homeostasis</p> Signup and view all the answers

    What is the key difference between reversible and irreversible enzyme inhibition?

    <p>Irreversible inhibition permanently binds to the enzyme, while reversible does not</p> Signup and view all the answers

    How are metabolic reactions organized within cells?

    <p>Metabolic reactions are organized into interconnected pathways</p> Signup and view all the answers

    What is the role of enzymes in metabolic pathways?

    <p>Enzymes determine the order of reactions in a pathway</p> Signup and view all the answers

    How does feedback inhibition regulate the activity of a metabolic pathway?

    <p>Feedback inhibition shuts down the pathway when the final product is abundant</p> Signup and view all the answers

    Which of the following statements about enzymes is NOT true?

    <p>Enzymes increase the activation energy of a reaction by separating substrates</p> Signup and view all the answers

    At the point of saturation, what is the state of the enzyme and substrate?

    <p>All enzyme molecules are bound to substrate molecules</p> Signup and view all the answers

    What is the primary role of an enzyme's active site?

    <p>To bind the substrate(s) and stabilize the transition state</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between enzyme and substrate concentrations?

    <p>Substrate concentration is usually much higher than enzyme concentration</p> Signup and view all the answers

    How is the efficiency of an enzyme typically measured?

    <p>By the rate at which it can convert substrate to product</p> Signup and view all the answers

    What is the range of turnover rates for enzymes?

    <p>1 to 40 million molecules per second</p> Signup and view all the answers

    Which of the following actions is performed by enzymes to facilitate a reaction?

    <p>Enzymes orient substrate molecules, bringing together the atoms that will bond</p> Signup and view all the answers

    What is the primary function of an enzyme's active site during a reaction?

    <p>To provide a template upon which the substrates are brought together in the proper position and orientation to react</p> Signup and view all the answers

    Which factor is NOT mentioned as a regulator of enzyme activity in the text?

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

    What happens to the noncovalent bonds in an enzyme at high temperatures?

    <p>They begin to break, leading to denaturation of the enzyme</p> Signup and view all the answers

    What type of inhibitor binds to a site on the enzyme other than the active site?

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

    What is the primary effect of nerve gas on the body?

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

    Which of the following is NOT a condition that can affect the secondary and tertiary structure of a protein?

    <p>Presence of cofactors</p> Signup and view all the answers

    What is the term used to describe the loss of a protein's three-dimensional structure and function?

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

    Which type of enzyme inhibitor covalently binds to the active site, permanently inactivating the enzyme?

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

    What is the primary function of enzyme inhibitors according to the text?

    <p>To regulate metabolic pathways</p> Signup and view all the answers

    What is the relationship between the free energy change (G) and the point of equilibrium for a chemical reaction?

    <p>The closer the reaction is to equilibrium, the more free energy is released.</p> Signup and view all the answers

    What is the purpose of coupling an endergonic reaction (G > 0) to an exergonic reaction (G < 0)?

    <p>To make the endergonic reaction occur spontaneously.</p> Signup and view all the answers

    What is the relationship between the hydrolysis of ATP and the formation of glucose 6-phosphate in terms of free energy change (G)?

    <p>The hydrolysis of ATP has a greater absolute value of G than the formation of glucose 6-phosphate.</p> Signup and view all the answers

    What is the role of enzymes in biological reactions?

    <p>Enzymes decrease the activation energy of reactions.</p> Signup and view all the answers

    What is the relationship between chemical equilibrium and the forward and reverse reactions?

    <p>At equilibrium, the forward and reverse reactions are balanced.</p> Signup and view all the answers

    What is the relationship between the free energy change (G) and the reversibility of a chemical reaction?

    <p>Reactions with G values near zero are characteristic of readily reversible reactions.</p> Signup and view all the answers

    What is the purpose of the high-energy phosphate bond in ATP?

    <p>The high-energy phosphate bond in ATP is used to activate endergonic processes.</p> Signup and view all the answers

    How do enzymes facilitate biologically important reactions?

    <p>Enzymes decrease the activation energy of reactions, allowing them to occur more quickly.</p> Signup and view all the answers

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