Anaerobic Respiration

• Anaerobic respiration occurs in the absence of oxygen. Only glycolysis takes place, therefore, only 2 molecules of ATP are produced.
• Glycolysis


  It is the first chemical pathway that occurs in cellular respiration. It takes place in the cytoplasm of the cell.

  
  

  Each glucose molecule is broken down into two pyruvate molecules and 2 ATP molecules.

  
  

  Glucose → 2 Pyruvate + 2 ATP
• Anaerobic Respiration

  A) Alcoholic

  B) Lactic Acid

  
• Anaerobic Respiration in Animals (and humans)

  It occurs when oxygen is in short supply; typically during prolonged exercise.

  
  

  The pyruvate formed in glycolysis is broken down into lactic acid. When lactic acid builds up, it causes muscle fatigue.

  
  

  The muscles need to stop working to allow the lactic acid to be broken down into CO2 and H2O when oxygen is available.

  
  

  Therefore, anaerobic respiration is NOT feasible long term.
• Anaerobic Respiration in Yeast and Bacteria

  In yeast and bacteria, anaerobic respiration is a way of life. In yeast, the pyruvate produced from glycolysis is broken down into ethanol (C2H5OH) and carbon dioxide (CO2).

  
  

  This process is also known as fermentation.

  
  

  The small energy yield of 2 ATP molecules is sufficient to meet the lifestyle needs of these organisms.
• Word Equation for Anaerobic Respiration in Animals and humans

  Glucose → Lactic Acid + ATP
• Word Equation for Anaerobic Respiration in Yeasts and Bacteria

  glucose → ethanol + carbon dioxide + ATP + heat