c5 p3

• Metabolism


  All chemical reactions in the body
• Catabolism


  Chemical reactions that break down complex organic molecules

  
• Anabolism


  Chemical reactions that build-up simple molecules into complex molecules
• All molecules have energy stored in the bonds between their atoms
• Chemical reactions depend on transfer of small amounts of energy from one molecule to another
• ATP


  A molecule for the temporary storage of energy
• Large amounts of energy are released when the terminal phosphate bond in ATP is hydrolysed (broken)
• Stages in Energy Generation

  1. Large molecules ® smaller units

  2. Smaller units are degraded to a few simple key compounds that play a central role in metabolism

  3. Citric acid (Krebs) cycle, and

  4. Oxidative Phosphorylation

  
• The oxidation of glucose is shown by the overall reaction: C6H12O6 + 6O2 à 6H2O + 6CO2 + 36 ATP + heat

  
• Glucose is catabolised in three pathways

  • Glycolysis
  • Krebs cycle
  • The electron transport chain & oxidative phosphorylation

  
• During digestion, polysaccs. & disaccs. are converted to monosaccs. (primarily glucose)

  
• CHO metabolism is primarily concerned with glucose metabolism
• Anaerobic


  ATP production in absence of O2: Glycolysis
• Aerobic


  ATP production using O2: Oxidative Phosphorylation

  
• Cellular Respiration


  Fuel + O2 ® CO2 + H2O + energy (ATP + heat)
• Cellular Respiration


  1. Glycolysis

  2. Formation of acetyl CoA as a transitional step

  3. Krebs cycle

  4. Electron transport chain

  
• Glycolysis


  1. Sugar activation

  2. Sugar cleavage

  3. Oxidation & ATP Formation
• If O2 is NOT available, PA accepts H2 from NADH2 to form lactic acid (maintains supplies of NAD+ for glycolysis to continue)
• If O2 is available, pyruvic acid prepares to enter Kreb's Cycle