Exploring Biological Energy Processes: Thermodynamics, Enzymes, Cellular Respiration, and Photosynthesis
A review sheet on biological energy processes, including thermodynamics, enzymes, cellular respiration, and photosynthesis.
Christopher Lee
Contributor
4.8
58
4 months ago
Preview (5 of 15)
Sign in to access the full document!
Exploring Biological Energy Processes: Thermodynamics, Enzymes,
Cellular Respiration, and Photosynthesis
Chapter 8
Thermodynamics, enzymes, and ATP
1. Definitions of First and Second Laws of Thermodynamics:
• First Law of Thermodynamics: Energy cannot be created or destroyed, only
transformed from one form to another. Total energy in the universe remains
constant.
• Second Law of Thermodynamics: The entropy (disorder) of an isolated
system tends to increase over time. In simpler terms, systems naturally
progress toward disorder or randomness.
2. Why Cells and Organisms are Considered Open Systems:
• Cells and organisms are open systems because they exchange energy and
matter with their surroundings. They take in nutrients and expel waste, and
require energy from the environment (like sunlight or food) to maintain their
structure and function.
3. Definition of Energy and Its Units:
• Energy: The capacity to do work or produce change. It exists in various
forms such as chemical, kinetic, and potential energy.
• Units of Energy: In biological systems, energy is often measured in
kilocalories (kcal) or kilojoules (kJ). The Joule (J) is the standard SI unit.
4. Definitions of Entropy (S), Free Energy (G), and Free Energy Change (ΔG):
• Entropy (S): A measure of disorder or randomness in a system.
• Free Energy (G): The energy available to do work in a system at constant
temperature and pressure.
Cellular Respiration, and Photosynthesis
Chapter 8
Thermodynamics, enzymes, and ATP
1. Definitions of First and Second Laws of Thermodynamics:
• First Law of Thermodynamics: Energy cannot be created or destroyed, only
transformed from one form to another. Total energy in the universe remains
constant.
• Second Law of Thermodynamics: The entropy (disorder) of an isolated
system tends to increase over time. In simpler terms, systems naturally
progress toward disorder or randomness.
2. Why Cells and Organisms are Considered Open Systems:
• Cells and organisms are open systems because they exchange energy and
matter with their surroundings. They take in nutrients and expel waste, and
require energy from the environment (like sunlight or food) to maintain their
structure and function.
3. Definition of Energy and Its Units:
• Energy: The capacity to do work or produce change. It exists in various
forms such as chemical, kinetic, and potential energy.
• Units of Energy: In biological systems, energy is often measured in
kilocalories (kcal) or kilojoules (kJ). The Joule (J) is the standard SI unit.
4. Definitions of Entropy (S), Free Energy (G), and Free Energy Change (ΔG):
• Entropy (S): A measure of disorder or randomness in a system.
• Free Energy (G): The energy available to do work in a system at constant
temperature and pressure.
• Free Energy Change (ΔG): The change in free energy during a process. A
negative ΔG indicates a spontaneous reaction, while a positive ΔG indicates a
non-spontaneous reaction.
5. Relationships Between ΔH, ΔG, and ΔS:
• ΔH (Change in Enthalpy): The heat content or total energy of a system.
• ΔG = ΔH - TΔS: This equation links the change in enthalpy, entropy, and
temperature to determine the spontaneity of a reaction.
o ΔG < 0: Exergonic reaction (spontaneous).
o ΔG > 0: Endergonic reaction (non-spontaneous).
6. Endergonic vs. Exergonic Reactions and Spontaneous Reactions:
• Endergonic Reactions: Reactions that require energy input (ΔG > 0), non-
spontaneous.
• Exergonic Reactions: Reactions that release energy (ΔG < 0), spontaneous.
• Spontaneous Reactions: Reactions that occur naturally without external
energy input, typically with a negative ΔG.
7. Equilibrium Constant (Keq) and Reaction at Equilibrium:
• Keq: The ratio of the concentrations of products to reactants at equilibrium.
• A reaction is at equilibrium when the rates of the forward and reverse
reactions are equal, and the concentrations of reactants and products remain
constant.
8. Equation Relating ΔG, Keq, and Substrate/Product Concentrations:
• ΔG = ΔG° + RT ln([products]/[reactants])
negative ΔG indicates a spontaneous reaction, while a positive ΔG indicates a
non-spontaneous reaction.
5. Relationships Between ΔH, ΔG, and ΔS:
• ΔH (Change in Enthalpy): The heat content or total energy of a system.
• ΔG = ΔH - TΔS: This equation links the change in enthalpy, entropy, and
temperature to determine the spontaneity of a reaction.
o ΔG < 0: Exergonic reaction (spontaneous).
o ΔG > 0: Endergonic reaction (non-spontaneous).
6. Endergonic vs. Exergonic Reactions and Spontaneous Reactions:
• Endergonic Reactions: Reactions that require energy input (ΔG > 0), non-
spontaneous.
• Exergonic Reactions: Reactions that release energy (ΔG < 0), spontaneous.
• Spontaneous Reactions: Reactions that occur naturally without external
energy input, typically with a negative ΔG.
7. Equilibrium Constant (Keq) and Reaction at Equilibrium:
• Keq: The ratio of the concentrations of products to reactants at equilibrium.
• A reaction is at equilibrium when the rates of the forward and reverse
reactions are equal, and the concentrations of reactants and products remain
constant.
8. Equation Relating ΔG, Keq, and Substrate/Product Concentrations:
• ΔG = ΔG° + RT ln([products]/[reactants])
Preview Mode
Sign in to access the full document!
100%