Ice

• Metabolism


  The sum of the chemical reactions in an organism
• Catabolism


  The energy-releasing processes

  
• Anabolism


  The energy-using processes
• Catabolism


  Provides the building blocks and energy for anabolism
• Metabolic pathway


  A sequence of enzymatically catalyzed chemical reactions in a cell
• Metabolic pathways


  • Determined by enzymes
  • Enzymes are encoded by genes
• Collision theory


  Chemical reactions can occur when atoms, ions, and molecules collide
• Activation energy


  Needed to disrupt electronic configurations
• Reaction rate


  The frequency of collisions with enough energy to bring about a reaction
• Reaction rate


  Can be increased by enzymes or by increasing temperature or pressure
• Enzymes


  • Biological catalysts
  • Specific for a chemical reaction; not used up in that reaction
• Cofactor


  Nonprotein component
• Coenzyme


  Organic cofactor
• Holoenzyme


  Apoenzyme plus cofactor
• Turnover number


  Generally 1-10,000 molecules per second
• Enzymes


  • Can be denatured by temperature and pH
• Competitive inhibition


  Inhibition of enzyme activity by a molecule that binds to the active site and prevents the substrate from binding

  
• Fermentation


  • Releases energy from oxidation of organic molecules
  • Does not require oxygen
  • Does not use the Krebs cycle or ETC
  • Uses an organic molecule as the final electron acceptor
• Types of fermentation


  • Alcohol fermentation: Produces ethyl alcohol + CO2
  • Lactic acid fermentation: Produces lactic acid
  • Homolactic fermentation: Produces lactic acid only
  • Heterolactic fermentation: Produces lactic acid and other compounds

  
• Protein catabolism


  1. Amino acids

  2. Extracellular proteases

  3. Krebs cycle

  4. Deamination, decarboxylation, dehydrogenation

  5. Organic acid
• Biochemical tests are used to identify bacteria
• Photosynthesis


  • Photo: Conversion of light energy into chemical energy (ATP)
  • Light-dependent (light) reactions
  • Synthesis: Fixing carbon into organic molecules
  • Light-independent (dark) reaction, Calvin-Benson cycle
• Oxygenic photosynthesis: 6 CO2 + 12 H2O + Light energy C6H12O6 + 6 H2O + 6 O2
• Anoxygenic photosynthesis: CO2 + 2 H2S + Light energy [CH2O] + H2O + 2 S0
• Chemotrophs using energy from chemicals

  1. Chemoheterotroph: Energy is used in anabolism

  2. Chemoautotroph, Thiobacillus ferroxidans: Energy used in the Calvin-Benson cycle to fix CO2

  
• Phototrophs using light energy

  1. Photoautotrophs use energy in the Calvin-Benson cycle to fix CO2

  2. Photoheterotrophs use energy
• Metabolic diversity among organisms

  • Photoautotroph: Light, CO2
  • Photoheterotroph: Light, Organic compounds
  • Chemoautotroph: Chemical, CO2
  • Chemoheterotroph: Chemical, Organic compounds