Ch. 5 Enzyme Structure and Function Quiz
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Questions and Answers

What defines a holoenzyme?

  • An apoenzyme combined with its cofactor (correct)
  • A protein portion without any cofactors
  • An enzyme that has been denatured
  • A non-protein component only

    • What essential molecule is required for maximizing ATP production during aerobic respiration?

  • Carbon Dioxide
  • Oxygen (correct)
  • NADH
  • Glucose

    • Which effect does high temperature have on enzyme activity?

  • Denatures proteins, slowing down enzyme activity (correct)
  • Promotes the formation of enzyme-substrate complexes
  • Increases enzyme activity consistently
  • Has no effect on enzyme activity

    • Which of the following accurately reflects a product of glucose breakdown in aerobic respiration?

    <p>Carbon Dioxide and Water</p> Signup and view all the answers

    How do competitive inhibitors function?

    <p>They fill the active site and prevent substrate binding</p> Signup and view all the answers

    What are the two hydrogen transport molecules produced during the breakdown of glucose?

    <p>NADH and FADH2</p> Signup and view all the answers

    In a redox reaction, what occurs during oxidation?

    <p>A loss of electrons occurs</p> Signup and view all the answers

    Which of the following statements about enzyme activity and substrate concentration is correct?

    <p>At high substrate concentration, enzyme activity reaches maximum rate</p> Signup and view all the answers

    Which of the following is NOT a step in the process of aerobic respiration?

    <p>Beta oxidation</p> Signup and view all the answers

    What is the role of non-competitive inhibitors in enzyme activity?

    <p>They can bind to the enzyme regardless of whether the substrate is present</p> Signup and view all the answers

    What is the end result of glucose breakdown during aerobic respiration?

    <p>Water and Carbon Dioxide</p> Signup and view all the answers

    During which step of aerobic respiration is pyruvate converted to acetyl-CoA?

    <p>Preparatory reaction</p> Signup and view all the answers

    Which statement describes the relationship between oxidation and reduction in metabolic pathways?

    <p>Oxidation and reduction occur simultaneously in paired reactions</p> Signup and view all the answers

    Which process illustrates the mutually beneficial relationship between plants and humans?

    <p>Plants provide glucose and oxygen while humans produce carbon dioxide.</p> Signup and view all the answers

    Which of these factors can denote protein denaturation?

    <p>Extreme temperature levels can alter protein structure</p> Signup and view all the answers

    What happens to energy when a terminal phosphate bond in ATP is broken?

    <p>Energy is released.</p> Signup and view all the answers

    Which of the following steps of aerobic respiration precedes the citric acid cycle?

    <p>Preparatory reaction</p> Signup and view all the answers

    Which of the following correctly describes the structure of ATP?

    <p>Three phosphate groups, ribose, and adenine.</p> Signup and view all the answers

    What does ATP hydrolysis typically drive in cellular processes?

    <p>Endergonic reactions.</p> Signup and view all the answers

    Which method of ADP phosphorylation involves direct energy from light?

    <p>Photophosphorylation.</p> Signup and view all the answers

    Which of the following statements about NAD+ and NADH is true?

    <p>NAD+ gains electrons and becomes NADH.</p> Signup and view all the answers

    What type of phosphorylation is catalyzed by specific enzymes and does not require the electron transport chain?

    <p>Substrate-level phosphorylation.</p> Signup and view all the answers

    Which statement best describes the role of ATP in cellular activities?

    <p>ATP is an energy shuttle that facilitates various cellular reactions.</p> Signup and view all the answers

    What is the final product of ATP hydrolysis?

    <p>ADP and a phosphate ion.</p> Signup and view all the answers

    What is the primary function of the citric acid cycle?

    <p>Generate ATP, NADH, and FADH2 from acetyl-CoA</p> Signup and view all the answers

    Where does glycolysis occur in eukaryotic cells?

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

    What are the products of one complete turn of the citric acid cycle from a single pyruvate molecule?

    <p>1 ATP, 3 NADH, 1 FADH2, 2 CO2</p> Signup and view all the answers

    Which component directly donates electrons to the electron transport chain?

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

    What is the net yield of ATP produced from glycolysis?

    <p>2 ATP</p> Signup and view all the answers

    What happens to pyruvate during pyruvate oxidation?

    <p>It combines with coenzyme A to form acetyl-CoA</p> Signup and view all the answers

    Which step of the cellular respiration process does not require oxygen?

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

    Which of the following is produced as a byproduct during the citric acid cycle?

    <p>Carbon dioxide</p> Signup and view all the answers

    During which phase of cellular respiration is the majority of ATP produced?

    <p>Electron transport chain</p> Signup and view all the answers

    What is the total yield of ATP from one glucose molecule after full aerobic respiration, including glycolysis, Krebs cycle, and the electron transport chain?

    <p>38 ATP</p> Signup and view all the answers

    What is the role of oxygen gas (O2) in the electron transport chain?

    <p>To serve as the final electron and hydrogen ion acceptor</p> Signup and view all the answers

    What effect does the binding of H+ ions to ATP synthase have?

    <p>It causes the rotor to spin, driving ATP synthesis</p> Signup and view all the answers

    Which of the following processes generates the most ATP during aerobic respiration?

    <p>Electron Transport Chain</p> Signup and view all the answers

    What term describes the gradient formed by the concentration of H+ ions across the membrane during the electron transport chain?

    <p>Proton-motive force</p> Signup and view all the answers

    How does the ATP synthase utilize the H+ ions to produce ATP?

    <p>By allowing H+ ions to flow through and drive rotation</p> Signup and view all the answers

    Which molecule is produced when oxygen combines with electrons and H+ ions at the end of the electron transport chain?

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

    What type of respiration involves breaking down glucose to generate ATP in the presence of oxygen?

    <p>Aerobic respiration</p> Signup and view all the answers

    What is the fate of lipids and proteins when they enter aerobic respiration?

    <p>They are broken down into pyruvic acid or Acetyl-CoA</p> Signup and view all the answers

    Study Notes

    Enzyme Structure and Function

    • Apoenzyme: The protein portion of an enzyme.
    • Cofactor: Non-protein component necessary for enzyme activity, often ions like Mg²⁺ or Ca²⁺.
    • Holoenzyme: Combination of an apoenzyme and its cofactor, representing the functional form.
    • Inhibitors: Substances that reduce enzyme activity, can be competitive or non-competitive.

    Factors Influencing Enzyme Activity

    • Temperature: High temperatures increase activity until denaturation occurs; low temperatures slow down the reaction.
    • pH: Extreme pH levels can denature enzymes, significantly affecting activity.
    • Substrate Concentration: High substrate concentration leads to maximum enzyme catalysis, termed saturation.

    Types of Inhibitors

    • Competitive Inhibitors: Compete with substrate for the active site, preventing formation of the enzyme-substrate complex.
    • Non-Competitive Inhibitors: Bind to allosteric sites on the enzyme, changing its activity without competing at the active site.

    Metabolism Overview

    • Metabolism includes catabolism (breaking down molecules) and anabolism (building molecules).
    • Involves enzymes, redox reactions (oxidation-reduction), and the production of energy carriers: ATP, NADH, and FADH₂.
    • Crucial processes include aerobic respiration and fermentation.

    Oxidation-Reduction Reactions

    • Oxidation: Loss of electrons that releases energy.
    • Reduction: Gain of electrons.
    • Redox Reaction: Pairing of oxidation and reduction processes essential in metabolic pathways.

    ATP: The Energy Currency

    • ATP (Adenosine Triphosphate): Acts as an energy shuttle; energy is released when the terminal phosphate bond is broken.
    • ATP Hydrolysis Reaction: ATP + H₂O → ADP + Pi + energy.
    • Structure includes ribose, adenine, and three phosphate groups.
    • ATP drives endergonic reactions through the transfer of phosphate groups.

    Phosphorylation of ADP

    • Converts ADP to ATP using energy input through:
      • Substrate-level phosphorylation: Direct enzymatic transfer of a phosphate group.
      • Oxidative phosphorylation: Energy from the electron transport chain.
      • Photophosphorylation: Light energy incorporated into ATP.

    Hydrogen Transport Molecules

    • NAD⁺ / NADH: NADH is the reduced form, generated by adding hydrogen to NAD⁺.
    • FAD / FADH₂: Similar role as NADH, functioning as electron carriers in metabolic reactions.
    • Both are essential for transporting electrons during respiration.

    Aerobic Respiration Stages

    • Glycolysis: Breakdown of glucose into 2 pyruvate, yielding 2 ATP and 2 NADH; occurs in cytoplasm.
    • Preparatory Reaction (Pyruvate Oxidation): Converts pyruvate into acetyl-CoA, producing 2 NADH.
    • Citric Acid Cycle (Krebs Cycle): Breaks down acetyl-CoA, generating 2 ATP, 6 NADH, and 2 FADH₂; cyclical process.
    • Electron Transport Chain (ETC): Utilizes NADH and FADH₂ to create a proton gradient, leading to ATP production (32 ATP per glucose molecule).

    Mitochondrial Function

    • Oxygen acts as the final electron acceptor in the ETC, producing water and maintaining the gradient for ATP synthesis.
    • ATP Synthase: Enzyme that harnesses the proton gradient to synthesize ATP through phosphorylation.

    Overall Yield of Aerobic Respiration

    • Total ATP generated from one glucose molecule is approximately 36 to 38 ATP, depending on transport efficiency across mitochondrial membranes.
    • Intermediate metabolites from carbohydrates, lipids, and proteins can enter aerobic respiration at various stages.

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    Ch.5 Metabolism - Biochemistry Notes PDF

    Description

    Test your knowledge on enzyme structure and function, including key terms like apoenzymes, cofactors, and the effects of inhibitors. Explore how temperature, pH, and substrate concentration influence enzyme activity. Perfect for biology students keen on understanding enzymatic processes!

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