Biological Science Eighth Edition Chapter 8
Title: Energy and Enzymes: An Introduction to Metabolism
Copyright © 2024 Pearson Education, Inc. All Rights Reserved
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
Focus on energy flow and transformation within biological systems.
Processes:
Photosynthesis: Converts solar energy into chemical energy.
Cellular respiration: Releases energy for cellular activities.
Chemical Components:
Inputs: CO₂, H₂O
Outputs: O₂, glucose, heat
Energy defined as the capacity to perform work.
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.
Diagram indicating forms of energy: Potential, Kinetic, and other types.
Summary: Energy changes forms but is conserved overall.
Focus on the roles of ions across membranes and the associated energy.
Potential energy relates to the configuration of shared electrons in molecules.
Examples: Photosynthesis and Respiration.
Product bonds that are shorter and stronger indicate a decrease in potential energy and the release of energy as thermal or light.
Energy stored in chemical bonds and gradients is classified as:
A) Kinetic energy
B) Thermal energy
C) Potential energy
Visualization related to energy types and chemical transformations.
Total entropy in a system always increases, indicating that energy transformations increase disorder.
Similar to earlier with emphasis on energy flow through photosynthesis and cellular respiration.
Gibbs Free Energy (G) predicts reaction spontaneity.
Equation: ΔG = ΔH - TΔS
ΔH: Change in enthalpy
ΔS: Change in entropy
T: Temperature
ΔG < 0: Spontaneous (Exergonic)
ΔG > 0: Nonspontaneous (Endergonic)
Equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Represents energy capture during photosynthesis.
Chemical reaction of glucose metabolism:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
ΔG: -686 kcal/mol in various conditions (e.g., liver cells, E. coli).
Photosynthesis process is classified as:
A) Exergonic
B) Endergonic
C) Spontaneous
D) Exergonic and spontaneous
E) Endergonic and spontaneous
Use of energetic coupling:
Exergonic reactions provide energy for endergonic reactions, making overall reactions spontaneous.
Visual representation of energetic coupling in biochemical reactions.
Reduction-Oxidation (Redox) Reactions: Transfer of energy via electron movement.
Oxidation: Loss of electrons (exergonic)
Reduction: Gain of electrons (endergonic)
Electrons can be completely transferred or repositioned within covalent bonds.
Electrons typically carried with protons (H+).
Reduction adds H, oxidation removes H.
FAD: Accepts electrons and protons to form FADH₂
NAD+: Accepts electrons and a proton to become NADH
Important for transferring electrons between molecules.
Visual of electron transfer processes in redox reactions.
NADH conversion to NAD+ + H+ indicates it has been:
a. Reduced
b. Oxidized
c. Phosphorylated
d. Glycosylated
e. Methylated
ATP (Adenosine Triphosphate): Primary energy carrier in cells; fuels cellular activities.
Hydrolysis of ATP to ADP and Pi releases substantial free energy:
ΔG = -7.3 kilocalories/mole ATP.
Exergonic phosphorylation couples with endergonic reactions to drive them forward.
Visualization of the coupling of exergonic and endergonic reactions through phosphorylating substrates.
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.
Diagram illustrating changes in free energy during a chemical reaction.
Role of enzyme:
To lower activation energy of a reaction (Ea).
Enzymes are protein catalysts specific to reactions:
Form an enzyme-substrate complex, leading to induced fit and activation energy reduction.
Substrates binding at active sites cause conformational changes, enhancing reactivity.
Visual illustrating enzyme effects on activation energy of a reaction.
Understanding diagrams that graphically represent activation energies.
A three-step process illustrating enzyme-substate complex formation leading to reaction progression.
Enzyme reaction speed increases with substrate concentration until saturation (Vmax).
Graph showing the relationship between substrate concentration and reaction velocity.
Saturation indicates high substrate occupancy, leading to max reaction velocity (Vmax).
Techniques for regulating enzyme activity:
Competitive inhibition: Inhibitor competes for active site.
Allosteric regulation: Molecule binds elsewhere, altering enzyme function.
Illustrative examples of competitive inhibition versus allosteric regulation and their impacts on enzyme function.
Visual representation of enzyme kinetic changes in the presence of inhibitors.
Example of metabolic pathways involving different enzymes and substrates, detailing their interactions.
Graphs depicting velocities in normal versus inhibited enzyme kinetics.
Query about competitive inhibitor effects on enzyme kinetics: a. Lowers Km b. Raises Km c. Lowers Vmax...
Continuation of graphical representation for KM with inhibitors.
Enzyme activity can be regulated through reversible or irreversible covalent modifications, such as phosphorylation.
Visualization of how phosphorylation alters enzyme structure and activity based on example pathways.
Metabolic pathways consist of sequences of enzymatic reactions, moving substrates through sequential transformations.
Example: A → B → C → D (enzymes 1 through 3 involved).
Catabolic pathways break down substrates to release energy (Exergonic).
Example reaction: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.
Anabolic pathways synthesize complex molecules; require energy input and must couple with exergonic reactions.
Example reaction: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
Dynamic regulation is demonstrated through feedback inhibition within metabolic pathways to maintain homeostasis.
Feedback inhibition example: enzyme inhibiting its own pathway production based on the product's concentration.
Visual depiction of feedback inhibition mechanisms regulating metabolic pathways.
Enzymes may require cofactors (inorganic ions) or coenzymes (organic molecules) to function optimally, affecting their activity.
List of examples of vitamins and their roles in enzyme activities, like Thiamine and Niacin.
Example: Vitamin C’s role in muscle formation, with deficiency leading to scurvy.
Example of scurvy symptoms due to vitamin C deficiency.
Acts in forming coenzymes NAD and NADP; deficiency leads to pellagra.
Conditions impacting enzyme efficiency include temperature and pH. Each enzyme has optimal parameters.
Different enzymes perform best at varying temperatures and pH levels as evidenced by comparative activity charts.
07-09 Ch 8 Energy and Enzymes A R
Biological Science Eighth Edition Chapter 8
Title: Energy and Enzymes: An Introduction to Metabolism
Copyright © 2024 Pearson Education, Inc. All Rights Reserved
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
Focus on energy flow and transformation within biological systems.
Processes:
Photosynthesis: Converts solar energy into chemical energy.
Cellular respiration: Releases energy for cellular activities.
Chemical Components:
Inputs: CO₂, H₂O
Outputs: O₂, glucose, heat
Energy defined as the capacity to perform work.
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.
Diagram indicating forms of energy: Potential, Kinetic, and other types.
Summary: Energy changes forms but is conserved overall.
Focus on the roles of ions across membranes and the associated energy.
Potential energy relates to the configuration of shared electrons in molecules.
Examples: Photosynthesis and Respiration.
Product bonds that are shorter and stronger indicate a decrease in potential energy and the release of energy as thermal or light.
Energy stored in chemical bonds and gradients is classified as:
A) Kinetic energy
B) Thermal energy
C) Potential energy
Visualization related to energy types and chemical transformations.
Total entropy in a system always increases, indicating that energy transformations increase disorder.
Similar to earlier with emphasis on energy flow through photosynthesis and cellular respiration.
Gibbs Free Energy (G) predicts reaction spontaneity.
Equation: ΔG = ΔH - TΔS
ΔH: Change in enthalpy
ΔS: Change in entropy
T: Temperature
ΔG < 0: Spontaneous (Exergonic)
ΔG > 0: Nonspontaneous (Endergonic)
Equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Represents energy capture during photosynthesis.
Chemical reaction of glucose metabolism:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
ΔG: -686 kcal/mol in various conditions (e.g., liver cells, E. coli).
Photosynthesis process is classified as:
A) Exergonic
B) Endergonic
C) Spontaneous
D) Exergonic and spontaneous
E) Endergonic and spontaneous
Use of energetic coupling:
Exergonic reactions provide energy for endergonic reactions, making overall reactions spontaneous.
Visual representation of energetic coupling in biochemical reactions.
Reduction-Oxidation (Redox) Reactions: Transfer of energy via electron movement.
Oxidation: Loss of electrons (exergonic)
Reduction: Gain of electrons (endergonic)
Electrons can be completely transferred or repositioned within covalent bonds.
Electrons typically carried with protons (H+).
Reduction adds H, oxidation removes H.
FAD: Accepts electrons and protons to form FADH₂
NAD+: Accepts electrons and a proton to become NADH
Important for transferring electrons between molecules.
Visual of electron transfer processes in redox reactions.
NADH conversion to NAD+ + H+ indicates it has been:
a. Reduced
b. Oxidized
c. Phosphorylated
d. Glycosylated
e. Methylated
ATP (Adenosine Triphosphate): Primary energy carrier in cells; fuels cellular activities.
Hydrolysis of ATP to ADP and Pi releases substantial free energy:
ΔG = -7.3 kilocalories/mole ATP.
Exergonic phosphorylation couples with endergonic reactions to drive them forward.
Visualization of the coupling of exergonic and endergonic reactions through phosphorylating substrates.
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.
Diagram illustrating changes in free energy during a chemical reaction.
Role of enzyme:
To lower activation energy of a reaction (Ea).
Enzymes are protein catalysts specific to reactions:
Form an enzyme-substrate complex, leading to induced fit and activation energy reduction.
Substrates binding at active sites cause conformational changes, enhancing reactivity.
Visual illustrating enzyme effects on activation energy of a reaction.
Understanding diagrams that graphically represent activation energies.
A three-step process illustrating enzyme-substate complex formation leading to reaction progression.
Enzyme reaction speed increases with substrate concentration until saturation (Vmax).
Graph showing the relationship between substrate concentration and reaction velocity.
Saturation indicates high substrate occupancy, leading to max reaction velocity (Vmax).
Techniques for regulating enzyme activity:
Competitive inhibition: Inhibitor competes for active site.
Allosteric regulation: Molecule binds elsewhere, altering enzyme function.
Illustrative examples of competitive inhibition versus allosteric regulation and their impacts on enzyme function.
Visual representation of enzyme kinetic changes in the presence of inhibitors.
Example of metabolic pathways involving different enzymes and substrates, detailing their interactions.
Graphs depicting velocities in normal versus inhibited enzyme kinetics.
Query about competitive inhibitor effects on enzyme kinetics: a. Lowers Km b. Raises Km c. Lowers Vmax...
Continuation of graphical representation for KM with inhibitors.
Enzyme activity can be regulated through reversible or irreversible covalent modifications, such as phosphorylation.
Visualization of how phosphorylation alters enzyme structure and activity based on example pathways.
Metabolic pathways consist of sequences of enzymatic reactions, moving substrates through sequential transformations.
Example: A → B → C → D (enzymes 1 through 3 involved).
Catabolic pathways break down substrates to release energy (Exergonic).
Example reaction: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.
Anabolic pathways synthesize complex molecules; require energy input and must couple with exergonic reactions.
Example reaction: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
Dynamic regulation is demonstrated through feedback inhibition within metabolic pathways to maintain homeostasis.
Feedback inhibition example: enzyme inhibiting its own pathway production based on the product's concentration.
Visual depiction of feedback inhibition mechanisms regulating metabolic pathways.
Enzymes may require cofactors (inorganic ions) or coenzymes (organic molecules) to function optimally, affecting their activity.
List of examples of vitamins and their roles in enzyme activities, like Thiamine and Niacin.
Example: Vitamin C’s role in muscle formation, with deficiency leading to scurvy.
Example of scurvy symptoms due to vitamin C deficiency.
Acts in forming coenzymes NAD and NADP; deficiency leads to pellagra.
Conditions impacting enzyme efficiency include temperature and pH. Each enzyme has optimal parameters.
Different enzymes perform best at varying temperatures and pH levels as evidenced by comparative activity charts.