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.