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07-09 Ch 8 Energy and Enzymes A R

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07-09 Ch 8 Energy and Enzymes A R

Page 1: Chapter Title

  • Biological Science Eighth Edition Chapter 8

  • Title: Energy and Enzymes: An Introduction to Metabolism

  • Copyright © 2024 Pearson Education, Inc. All Rights Reserved

Page 2: Chapter 8 Opening Roadmap

  • Learning Objectives:

    • Understand how enzymes utilize energy to facilitate chemical reactions.

    • Explore different aspects of energy and enzymes.

      • Key Questions:

        • What happens to energy in chemical reactions?

        • How do enzymes influence chemical reaction rates?

        • Can chemical energy drive nonspontaneous reactions?

        • What factors impact enzyme function?

        • How do enzymes collaborate in metabolic pathways?

  • Copyright © 2024 Pearson Education, Inc. All Rights Reserved

Page 3: Bioenergetics

  • Focus on energy flow and transformation within biological systems.

Page 4: Bioenergetics - Carbon Cycle / Trophic Interactions

  • Processes:

    • Photosynthesis: Converts solar energy into chemical energy.

    • Cellular respiration: Releases energy for cellular activities.

  • Chemical Components:

    • Inputs: CO₂, H₂O

    • Outputs: O₂, glucose, heat

Page 5: Energy is the Ability to Do Work

  • Energy defined as the capacity to perform work.

Page 6: Energy in Chemical Reactions

  • Types of energy:

    • Kinetic Energy: Energy of motion.

    • Thermal Energy: Energy associated with molecular movement.

    • Potential Energy: Stored energy, dependent on position or configuration.

    • Chemical Energy: Energy stored in chemical bonds and gradients.

  • 1st Law of Thermodynamics: Energy cannot be created or destroyed, only transferred or transformed.

Page 7: Types of Energy

  • Diagram indicating forms of energy: Potential, Kinetic, and other types.

  • Summary: Energy changes forms but is conserved overall.

Page 8: Chemical Reactions and Energy Transformations

  • Focus on the roles of ions across membranes and the associated energy.

Page 9: Energy Transformations During Chemical Reactions

  • Potential energy relates to the configuration of shared electrons in molecules.

  • Examples: Photosynthesis and Respiration.

Page 10: Energy Transformations in Reactions

  • Product bonds that are shorter and stronger indicate a decrease in potential energy and the release of energy as thermal or light.

Page 11: Clicker Question

  • Energy stored in chemical bonds and gradients is classified as:

    • A) Kinetic energy

    • B) Thermal energy

    • C) Potential energy

Page 12: Figure 8.3

  • Visualization related to energy types and chemical transformations.

Page 13: Second Law of Thermodynamics

  • Total entropy in a system always increases, indicating that energy transformations increase disorder.

Page 14: Reiteration of Carbon Cycle / Trophic Interactions

  • Similar to earlier with emphasis on energy flow through photosynthesis and cellular respiration.

Page 15: Gibbs Free Energy

  • Gibbs Free Energy (G) predicts reaction spontaneity.

    • Equation: ΔG = ΔH - TΔS

      • ΔH: Change in enthalpy

      • ΔS: Change in entropy

      • T: Temperature

Page 16: Spontaneous vs Nonspontaneous Reactions

    • ΔG < 0: Spontaneous (Exergonic)

    • ΔG > 0: Nonspontaneous (Endergonic)

Page 17: Photosynthesis Reaction

  • Equation:

    • 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

    • Represents energy capture during photosynthesis.

Page 18: Energy Release in Cellular Respiration

  • Chemical reaction of glucose metabolism:

    • C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

    • ΔG: -686 kcal/mol in various conditions (e.g., liver cells, E. coli).

Page 19: Clicker Question

  • Photosynthesis process is classified as:

    • A) Exergonic

    • B) Endergonic

    • C) Spontaneous

    • D) Exergonic and spontaneous

    • E) Endergonic and spontaneous

Page 20: Driving Nonspontaneous Reactions

  • Use of energetic coupling:

    • Exergonic reactions provide energy for endergonic reactions, making overall reactions spontaneous.

Page 21: Figure 8.5

  • Visual representation of energetic coupling in biochemical reactions.

Page 22: Redox Reactions

  • Reduction-Oxidation (Redox) Reactions: Transfer of energy via electron movement.

    • Oxidation: Loss of electrons (exergonic)

    • Reduction: Gain of electrons (endergonic)

Page 23: Electron Transfer in Redox Reactions

  • Electrons can be completely transferred or repositioned within covalent bonds.

Page 24: Understanding Redox Further

  • Electrons typically carried with protons (H+).

    • Reduction adds H, oxidation removes H.

Page 25: Electron Carriers

  • FAD: Accepts electrons and protons to form FADH₂

  • NAD+: Accepts electrons and a proton to become NADH

  • Important for transferring electrons between molecules.

Page 26: Figure 8.7

  • Visual of electron transfer processes in redox reactions.

Page 27: Clicker Question

  • NADH conversion to NAD+ + H+ indicates it has been:

    • a. Reduced

    • b. Oxidized

    • c. Phosphorylated

    • d. Glycosylated

    • e. Methylated

Page 28: ATP as Energy Currency

  • ATP (Adenosine Triphosphate): Primary energy carrier in cells; fuels cellular activities.

Page 29: ATP Hydrolysis

  • Hydrolysis of ATP to ADP and Pi releases substantial free energy:

    • ΔG = -7.3 kilocalories/mole ATP.

Page 30: Coupling of ATP Hydrolysis to Endergonic Reactions

  • Exergonic phosphorylation couples with endergonic reactions to drive them forward.

Page 31: Exergonic Phosphorylation

  • Visualization of the coupling of exergonic and endergonic reactions through phosphorylating substrates.

Page 32: How Enzymes Work

  • Enzyme-catalyzed reactions require reactants to collide correctly with proper orientation and bond strain.

    • Reactant rate increased by heat or catalysts that lower activation energy.

Page 33: Figure 8.11

  • Diagram illustrating changes in free energy during a chemical reaction.

Page 34: Enzyme Role in Cells

  • Role of enzyme:

    • To lower activation energy of a reaction (Ea).

Page 35: Enzyme Substrates Interaction

  • Enzymes are protein catalysts specific to reactions:

    • Form an enzyme-substrate complex, leading to induced fit and activation energy reduction.

Page 36: Enzyme Action Mechanism

  • Substrates binding at active sites cause conformational changes, enhancing reactivity.

Page 37: Figure 8.13

  • Visual illustrating enzyme effects on activation energy of a reaction.

Page 38: Activation Energy Graph Interpretation

  • Understanding diagrams that graphically represent activation energies.

Page 39: Enzyme Action Process

  • A three-step process illustrating enzyme-substate complex formation leading to reaction progression.

Page 40: Catalysis Rate Limitations

  • Enzyme reaction speed increases with substrate concentration until saturation (Vmax).

Page 41: Reaction Velocity Illustration

  • Graph showing the relationship between substrate concentration and reaction velocity.

Page 42: Enzyme Kinetics Detail

  • Saturation indicates high substrate occupancy, leading to max reaction velocity (Vmax).

Page 43: Enzyme Regulation Types

  • Techniques for regulating enzyme activity:

    • Competitive inhibition: Inhibitor competes for active site.

    • Allosteric regulation: Molecule binds elsewhere, altering enzyme function.

Page 44: Figure 8.17

  • Illustrative examples of competitive inhibition versus allosteric regulation and their impacts on enzyme function.

Page 45: Enzyme Kinetics with Inhibition

  • Visual representation of enzyme kinetic changes in the presence of inhibitors.

Page 46: Enzyme Kinetics Example

  • Example of metabolic pathways involving different enzymes and substrates, detailing their interactions.

Page 47: Enzyme Kinetics Continued

  • Graphs depicting velocities in normal versus inhibited enzyme kinetics.

Page 48: Enzyme Regulation Question

  • Query about competitive inhibitor effects on enzyme kinetics: a. Lowers Km b. Raises Km c. Lowers Vmax...

Page 49: Enzyme Kinetics with Inhibition Continued

  • Continuation of graphical representation for KM with inhibitors.

Page 50: Covalent Modifications in Enzyme Regulation

  • Enzyme activity can be regulated through reversible or irreversible covalent modifications, such as phosphorylation.

Page 51: Figure 8.18

  • Visualization of how phosphorylation alters enzyme structure and activity based on example pathways.

Page 52: Metabolic Pathways Overview

  • Metabolic pathways consist of sequences of enzymatic reactions, moving substrates through sequential transformations.

    • Example: A → B → C → D (enzymes 1 through 3 involved).

Page 53: Catabolic Pathways

  • Catabolic pathways break down substrates to release energy (Exergonic).

    • Example reaction: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.

Page 54: Anabolic Pathways

  • Anabolic pathways synthesize complex molecules; require energy input and must couple with exergonic reactions.

    • Example reaction: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.

Page 55: Regulation of Metabolic Pathways

  • Dynamic regulation is demonstrated through feedback inhibition within metabolic pathways to maintain homeostasis.

Page 56: Feedback Inhibition in Metabolism

  • Feedback inhibition example: enzyme inhibiting its own pathway production based on the product's concentration.

Page 57: Figure 8.19

  • Visual depiction of feedback inhibition mechanisms regulating metabolic pathways.

Page 58: Enzyme Regulation by Non-enzymatic Molecules

  • Enzymes may require cofactors (inorganic ions) or coenzymes (organic molecules) to function optimally, affecting their activity.

Page 59: Examples of Cofactors and Coenzymes

  • List of examples of vitamins and their roles in enzyme activities, like Thiamine and Niacin.

Page 60: Importance of Cofactors

  • Example: Vitamin C’s role in muscle formation, with deficiency leading to scurvy.

Page 61: Cofactors: Enzyme "Helpers"

  • Example of scurvy symptoms due to vitamin C deficiency.

Page 62: Vitamin B3 Role in Enzymes

  • Acts in forming coenzymes NAD and NADP; deficiency leads to pellagra.

Page 63: Factors Affecting Enzyme Function

  • Conditions impacting enzyme efficiency include temperature and pH. Each enzyme has optimal parameters.

Page 64: Enzyme Optimal Activity

  • Different enzymes perform best at varying temperatures and pH levels as evidenced by comparative activity charts.