Nitrogen cycle

• Recycling of chemicals


  Constant process on the planet
• Microorganisms such as bacteria

  • Play a key role in recycling chemicals
  • Break down complex organic molecules
  • Return elements to the environment to be reused
• Elements


  Recycle between the living world and the non-living world
• Elements that recycle


  • Carbon
  • Nitrogen
• Nitrogen


  Very important element needed to make many biological compounds such as DNA, proteins, amino acids, and vitamins
• 78% of the air is nitrogen
• Nitrogen gas is unreactive and we cannot do anything with it
• Nitrogen fixation


  1. Bacteria in the soil or root nodules of legumes convert nitrogen gas into nitrates

  2. Lightning strikes the ground can also fix nitrogen gas into nitrates
• Nitrates


  Form that plants can use
• Decomposition


  Decomposing bacteria break down dead organisms and release nitrogen in the form of ammonia back into the soil
• Nitrification


  Ammonia is converted to nitrites then to nitrates by nitrifying bacteria
• Denitrification


  Denitrifying bacteria convert excess nitrates in the soil back into nitrogen gas in the atmosphere
• Bacteria involved in the nitrogen cycle

  • Nitrogen fixing bacteria
  • Decomposing bacteria
  • Nitrifying bacteria
  • Denitrifying bacteria