Nitrogenous Wastes

• Nitrogenous Wastes

  Metabolic waste products that contain nitrogen; the result of the metabolic breakdown of proteins and nucleic acids
• Excretion 


  The removal of nitrogenous wastes

  • elimination of nitrogenous wastes is essential - ammonia is extremely toxic and a build up of it in cells can affect the pH (enzymes can denature and compromise their function and reduce metabolic activity)
• Ammonia

  • 1st nitrogenous waste formed from the breakdown of proteins
  • can be converted into urea or uric acid
  • small molecule
  • highly toxic
  • very soluble
  • low energy cost
  • eg. most aquatic animals (fish) that can afford to lose water
• Urea

  • larger molecule
  • less toxic
  • soluble
  • converting ammonia to urea requires energy
  • eg. mammals, amphibians (need to conserve water)
• Uric Acid

  • highly insoluble
  • least toxic
  • requires the most energy to convert from ammonia
  • can be excreted as a paste to conserve water
  • eg. birds, insects