Unit 2 - BIOL 402

• Energy and metabolism


  An organism takes food, digests it, and converts it into energy that can be used to perform some type of work
• Metabolic pathways


  All of the metabolism functions in our bodies right now
• Basic biochemical pathway


  1. Reaction 1: enzyme 1 (precursor)

  2. Reaction 2: enzyme 2 (intermediates)

  3. Reaction 3: enzyme 3 (product), enzyme 4 (product)

  
• Precursor


  Starting molecule
• Intermediates


  B and C molecules
• Bioenergetics


  The study of energy conversion
• Energy


  The capacity to do work or cause change
• Kinetic energy


  Energy of motion
• Potential energy


  Stored energy
• Everything technically has kinetic energy, and energy that is not kinetic is potential energy
• Chemical energy


  The potential energy in chemical bonds, released by chemical reactions
• Chemical energy examples


  • CH4 has high potential energy due to its single bonds
  • CO2 has low potential energy due to its double bonds
• Energy transformation is part of thermodynamics
• 1st law of thermodynamics


  Energy is neither created or destroyed, but energy can be transferred
• 2nd law of thermodynamics

  The dispersal or disorder of matter increases, entropy increases
• Gibbs free energy


  The energy in a system, not the surroundings. Free energy = the available energy in a chemical reaction
• Enthalpy


  The change in the total energy of a system
• Entropy


  A change in the disorder of the matter in a system. High S = messy room, low S = clean room
• If delta G is (-)

  The reaction is spontaneous, energy is released, energy is released = exergonic reaction
• Exergonic reaction example


  • CH4 + 2O2 -> CO2 + 2H2O, converting high potential energy into low potential energy (due to their bonds)
• If delta G is (+)


  The reaction is non spontaneous, energy is consumed, energy is required = endergonic reaction
• Cellular work


  Chemical work, transport work, mechanical work
• ATP


  Adenosine triphosphate, the immediate energy source for cellular work

  
• ATP hydrolysis


  Adenosine (base) undergoes hydrolysis (adding water to break apart) to produce adenosine diphosphate (exergonic reaction)

  
• Reaction coupling


  An exergonic reaction (ATP hydrolysis) is coupled closely to an endergonic reaction, exergonic releases energy that goes to the endergonic reaction
• Reaction coupling example


  • Glutamic acid conversion to glutamine - glutamine synthesis from glutamic acid by itself is non spontaneous, but the free energy change for the coupled reaction with ATP hydrolysis gives the overall spontaneous reaction

  
• Protein kinase


  A type of enzyme in biology, -ase ending = type of enzyme
• Activation energy


  The minimum amount of energy required to start a chemical reaction, higher Ea = slower reaction

  
• Transition State


  A temporary state of maximum energy in a reaction
• Enzymes


  • Biological catalysts that speed up reactions without heating by lowering the activation energy, they do not add energy/heat into the reaction

  
• Active site


  The location of an enzyme where substrates "bind" and undergo a chemical reaction

  
• Enzymes change shape after substrate binding, similar to a puzzle being a different shape when the pieces are separated vs. when they are bound together

  
• Enzymes are very substrate specific, L-Alanine Oxidase & L-Alanine fit together but L-Alanine Oxidase & D-Alanine do not fit

  
• Cofactor


  A non protein substance required for enzyme activity, including inorganic cofactors (ions) and coenzymes (organic)
• Normal binding


  A substrate that binds normally to the active site of an enzyme
• Competitive inhibitor


  A piece that mimics the substrate and competes for a spot in the active site
• Noncompetitive inhibitor


  Binds to the enzyme away from the active site, causing the enzyme to be altered
• Enzyme kinetics


  The study of the rates of enzyme-catalyzed chemical reactions

  
• Factors that affect the rate of enzyme-catalyzed reactions

  • Substrate concentration
  • pH
  • Temperature
  • Inhibitors and activators

  
• Allosteric regulation


  Function at one site of a protein is affected by the binding of an inhibitor or activator to a different site