Biochemistry: Enzymes and Their Function
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Questions and Answers

What is a key characteristic of enzymes compared to other chemical cofactors?

  • Enzymes change the results of reactions
  • Enzymes have a high degree of specialization (correct)
  • Enzymes are less efficient than other cofactors
  • Enzymes cannot perform reactions multiple times

    • What occurs to the enzyme at the end of a reaction?

  • It gets consumed in the reaction
  • It transforms into a different molecule
  • It is modified by the substrate
  • It returns to its original state (correct)

    • How do enzymes affect the speed of biochemical reactions?

  • They prevent reactions from occurring
  • They slow down the reaction significantly
  • They increase reaction speed by thousands to millions of times (correct)
  • They have a minimal effect on speed

    • What role does Mg2+ play in the interaction between ATP and glucose?

    <p>It holds ATP in one area of the active site.</p> Signup and view all the answers

    What type of substances can an enzyme specifically act upon?

    <p>Specific substrates that fit perfectly</p> Signup and view all the answers

    What occurs when glucose enters the active site of the enzyme?

    <p>A conformational change in the enzyme takes place.</p> Signup and view all the answers

    Why are enzyme levels in blood clinically significant?

    <p>They indicate the presence of specific diseases</p> Signup and view all the answers

    Which of the following statements about enzyme names is correct?

    <p>Names can describe both substrate and function.</p> Signup and view all the answers

    What occurs during the breaking of glycosidic, ester, or peptide bonds?

    <p>Hydroxyl and hydrogen atoms are added</p> Signup and view all the answers

    What is the classification number EC:(2.7.1.1) indicating for hexokinase?

    <p>It transfers phosphate groups.</p> Signup and view all the answers

    How does an enzyme differ from a catalyst?

    <p>Enzymes are specific to certain reactions and substrates</p> Signup and view all the answers

    What happens to the enzyme after glucose-6-phosphate is formed?

    <p>It moves away due to reduced attraction to products.</p> Signup and view all the answers

    What effect does an increase in temperature have on an enzyme-catalyzed reaction at low temperatures?

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

    How does the active site of an enzyme lower the activation energy?

    <p>By stabilizing the enzyme-substrate complex.</p> Signup and view all the answers

    Which of the following classes of enzymes is hexokinase categorized under?

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

    What happens to the reaction velocity as the concentration of products increases?

    <p>The reaction velocity decreases.</p> Signup and view all the answers

    Which type of inhibition allows the enzyme activity to be regained after the inhibitor is removed?

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

    What is the outcome when glucose and ATP interact in the enzyme's active site?

    <p>Glucose is converted into glucose-6-phosphate, and ADP is produced.</p> Signup and view all the answers

    What is the characteristic of competitive inhibitors?

    <p>They compete with the substrate for the active site.</p> Signup and view all the answers

    What is the outcome when the temperature exceeds the optimum range for an enzyme?

    <p>The enzyme is denatured.</p> Signup and view all the answers

    Which factor is responsible for decreasing the number of free enzymes available to react with substrate when a competitive inhibitor is present?

    <p>The binding of the inhibitor to the enzyme.</p> Signup and view all the answers

    In which condition would reaction completion reach 100%?

    <p>When products are removed as fast as they are formed.</p> Signup and view all the answers

    Which statement best describes noncompetitive inhibition?

    <p>It can happen regardless of substrate concentration.</p> Signup and view all the answers

    What effect does increasing substrate concentration have on enzyme activity until saturation is reached?

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

    What is the term for the maximum velocity of an enzymatic reaction when the binding sites are fully saturated?

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

    How does increasing enzyme concentration affect the rate of reaction?

    <p>It decreases competition for active sites.</p> Signup and view all the answers

    What role does vitamin C in lemon juice play when applied to sliced apples?

    <p>It inhibits browning by changing pH.</p> Signup and view all the answers

    What condition describes an enzyme operating at peak activity?

    <p>Steady state</p> Signup and view all the answers

    What is Km in the context of an enzymatic reaction?

    <p>Half the maximum velocity of the enzyme</p> Signup and view all the answers

    What happens to the enzyme activity when all active sites are full?

    <p>Enzyme activity stops increasing.</p> Signup and view all the answers

    Which factor is NOT typically a condition affecting enzyme activity?

    <p>Volume of liquid in the reaction</p> Signup and view all the answers

    What is the mechanism of action of an irreversible inhibitor?

    <p>It forms a covalent bond with an amino acid side chain in the active site.</p> Signup and view all the answers

    Which heavy metals are known to act as irreversible inhibitors?

    <p>Silver, mercury, and lead.</p> Signup and view all the answers

    How does penicillin function as an antibiotic?

    <p>It inhibits bacteria by binding to enzymes that synthesize cell walls.</p> Signup and view all the answers

    What is meant by the term saturation in enzyme kinetics?

    <p>The maximum rate of reaction when enzyme active sites are fully occupied.</p> Signup and view all the answers

    Which factors are crucial for enzyme-substrate interactions?

    <p>Conformation of proteins and positions of side chains.</p> Signup and view all the answers

    Why is understanding kinetic parameters important in biotechnology?

    <p>To optimize enzyme reactions for faster substrate conversion.</p> Signup and view all the answers

    What happens to enzyme activity when an irreversible inhibitor is present?

    <p>The enzyme becomes permanently inactive and cannot catalyze reactions.</p> Signup and view all the answers

    Which of the following best describes enzyme kinetics?

    <p>It studies the influence of substrate concentration on product formation.</p> Signup and view all the answers

    Study Notes

    Enzyme Function and Characteristics

    • Enzymes are highly efficient biological catalysts, operating at up to one million reactions per minute.
    • Enzymes bind specific substrates, exhibiting a high degree of specialization for substrates and reactions.
    • Enzymes return to their original state after reactions, distinguishing them from other chemical cofactors.

    Reactions Catalyzed by Enzymes

    • Various enzymes catalyze the hydrolysis of glycosidic, ester, and peptide bonds in carbohydrates, lipids, and proteins.
    • The process typically involves breaking bonds through the addition of water, leading to chemical changes.

    Roles of Enzymes

    • Enzymes are crucial in metabolism, diagnostics, and therapeutics within living organisms.
    • Enzyme concentration in blood can be diagnostically significant, aiding in medical diagnoses.
    • Example: Glucose interacts with ATP in enzyme active sites, with structural changes facilitating product release.

    Enzyme Nomenclature

    • Most enzyme names end in "-ase"; sucrase, for instance, catalyzes sucrose hydrolysis.
    • Enzyme names often reflect their function or substrate; e.g., oxidases for oxidation reactions.
    • Common names are used for digestive enzymes, like pepsin and trypsin.

    Enzyme Classification System

    • Enzymes are categorized using a four-digit EC number system, indicating class, subclass, and specific function.
    • Example: EC (2.7.1.1) for D-Hexose-6-Phosphotransferase (Hexokinase).

    Factors Influencing Enzyme Activity

    • High substrate concentration increases enzyme activity until saturation occurs, reaching a maximum velocity (Vmax).
    • Km (Michaelis constant) represents substrate concentration at half of Vmax, indicating enzyme affinity for the substrate.
    • Enzyme activity is affected by temperature, pH, substrate concentration, enzyme concentration, product concentration, and time.

    Inhibition of Enzyme Activity

    • Inhibitors can be reversible or irreversible, impacting enzyme functionality.
    • Reversible inhibitors can be competitive (compete for the active site) or noncompetitive (bind elsewhere).
    • Irreversible inhibitors, such as certain heavy metals and penicillin, permanently deactivate enzymes by forming covalent bonds.

    Application in Medicine and Biotechnology

    • Antibiotics like penicillin inhibit bacterial enzymes vital for cell wall synthesis, halting bacterial infection.
    • Understanding enzyme kinetics is essential for optimizing enzymes in biotechnology applications.
    • Proper knowledge of kinetic parameters allows for the selection of enzymes that can maximize substrate conversion rates.

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    Enzymes Lecture Notes

    Description

    Explore the fascinating world of enzymes and their crucial role in biological reactions. This quiz delves into the specific characteristics of enzymes, including their unique substrates and how they enhance reaction speeds immensely. Test your understanding of the principles of enzymatic action and its significance in living organisms.

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