Thermodynamics

• What is the formula for Gibbs Free Energy?

  ΔG = ΔH - TΔS

  
• Who is Josiah Willard Gibbs?

  A scientist from 1839 to 1903
• What does a positive ΔH indicate?

  Energy is consumed in an endothermic reaction

  
• What is entropy (S) in a chemical system?

  The measure of randomness or disorder
• What does a high entropy indicate about a chemical system?

  The system is disordered
• What does ΔG < 0 indicate about a reaction?

  The reaction will proceed in the forward direction
• What does ΔG > 0 indicate about a reaction?

  The reaction will proceed in the backward direction
• What does ΔG = 0 indicate about a reaction?

  The reaction is in equilibrium

  
• What is chemical equilibrium?

  State where concentrations do not change over time
• What is dynamic equilibrium?

  Rates of forward and backward reactions are equal
• What does Le Chatelier's principle state?

  Equilibrium shifts to counteract imposed changes
• What does a catalyst do in a reaction?

  Speeds up the reaction without being consumed
• What is the role of enzymes in biochemical reactions?

  They act as protein catalysts
• What does ΔGbind represent?

  The Gibbs free energy change on binding

  
• What happens to water during ligand binding?

  Water is displaced from the ligand and receptor
• What is the effect of ligand binding on receptor conformation?

  Receptor is constrained to one conformation
• What does a large negative ΔGbind indicate?

  KA will be a large positive number
• What are the characteristics of dynamic equilibrium?

  • Forward and backward reaction rates are equal
  • Concentrations of reactants and products remain constant
  • No net change in concentrations
• What are the implications of Le Chatelier's principle?

  • Equilibrium shifts to counteract changes
  • Changes can be in concentration, temperature, volume, or pressure
  • New equilibrium is established
• What happens to the entropy of water during ligand binding?

  • Water is expelled from the binding site
  • Entropy of water increases
  • Binding involves enthalpic and entropic changes
• What is the effect of receptor-ligand binding on the receptor's conformation?

  • Receptor is constrained to one conformation
  • H-bonded water is expelled
  • Various intermolecular interactions occur