Aerobic respiration

• Glycolysis:

  • First stage of both types of respiration
  • Glucose is phosphorylated to glucose-6-phosphate using x2 ATP, releasing x2 ADP
  • Glucose-6-phosphate is converted into x2 Triose phosphate
  • Triose phosphate oxidised into x2 pyruvate with a net gain of 2 ATP (x4 ADP + Pi --> x4 ATP, x2 NAD --> x2 NADH)
• 1. Glycolysis (cytoplasm)
  2. Link reaction (Matrix)
  3. Krebs cycle (matrix)
  4. Electron transfer chain (cristae)
• Link reaction:

  • Pyruvate actively transported into the matrix
  • Pyruvate oxidised to acetate, releasing a molecule of carbon dioxide
  • Acetate and co-enzyme A react to form Acetyl coenzyme A (acetyl CoA) which enters the Krebs cycle
  • Some energy lost as heat
  • Some protons leak across the membrane
  • Some ATP used for the active transport of pyruvate into the mitochondria
• Mitochondrial diseases: Reduce the production of ATP by effecting the proteins involved, causing anaerobic respiration to occur. Lots of lactic acid is produced causing fatigue and weakness, some lactate can also enter the bloodstream.
• Krebs cycle:

  1. Acetyl CoA reacts with a 4c molecule to forms a 6C molecule that enters the cycle
  2. Co-enzyme A is released to the link reaction
  3. In a series of oxidation/reduction reactions reduced coenzymes (NADH & FADH2) are produced, ATP is produced by substrate level phosphorylation and CO2 is lost
  4. Coenzymes transfer electrons to the ETC

  
• Electron transfer chain:

  • Most ATP is generated here by oxidative phosphorylation
  • NADH & FADH2 release hydrogen ions and electrons
  • electrons pass down carriers releasing extra energy which is used to actively transport hydrogen ions from matrix to the intermembrane space
  • Electrochemical gradient established
  • hydrogen ions diffuse back into the matrix through ATP synthases, condensing ADP + Pi into ATP
  • Electrons combine with oxygen and hydrogen ions to form water
  • Oxygen is the final electron acceptor
• Measuring rate:

  • DV - measure volume of oxygen consumed in a given time
  • KOH (potassium hydroxide)- absorbs CO2 so only O2 consumption is causing changes in volume/pressure
  • Glass beads - Same volume/mass of organism, control to show mass is not causing change in volume of O2
  • Water bath to control temperature
  • Allow time for equilibrium of pressure and rate of respiration before recording
• When there is net CO2 given out, the rate of respiration is greater than the rate of photosynthesis so the plant looses mass.

  When there is net CO2 taken in, the rate of respiration is less than the rate of photosynthesis so the plant gains mass so the plant can grow.