5.2.5 Anaerobic Respiration

• In plants & microorganisms like yeast, pyruvate is converted into ethanol and CO2
• In animals, pyruvate is converted into lactate
• Production of Ethanol (plants + microorganisms)

  • Glycolysis occurs, forming pyruvate
  • Pyruvate lose a CO2 molecule and accepts hydrogen from NADH becoming ethanol
  • NADH therefore becomes oxidised

  
• Anerobic conditions in yeast has been exploited in the alcohol and brewing industry
• During the anaerobic respiration, the ATP produced is from glycolysis
• Production of lactate (animals)

  • Occurs commonly in muscles
  • Glycolysis occurs forming pyruvate
  • Pyruvate takes up 2 hydrogen atoms from NADH forming lactate
  • NADH becomes oxidised as a result
• Lactate is later oxidised back into pyruvate and can be further oxidised to release energy or be converted into glycogen
• NAD is regenerated when it it is oxidised in anaerobic respiration and is reduced during glycolysis
• The production of lactic acid by muscle cells under anaerobic conditions causes fatigue because the build-up of lactic acid makes the pH more acidic which inhibits enzymes involved in contraction