The Nitrogen Cycle

The Nitrogen Cycle

1. Nitrogen Fixing

   • In Root Nodules in plants
     • Leguminouse plants
     • Mutalistic
     • Rhizobium
     • When a leguminouse plant germinates it procues a protein called lectin which binds to polysacharides in the bateria cell wall. Bacteria invade root and spread along root hairs , stimulating some of the roots to divide and produce small lumps called nodules where bacteria colonise
     • Nitrogenase
       • Turns N2 into ammonium ions
         • Needs ATP, Hydrogen andAna Cond
           • ATP from metabolism of sucrose in leafs during photosynth transported down to nodules then processed and respired to make atp Hydrogen from redNADP  Legheamoglobin = ananrobic conditions 
   • In Soil
     • Rhizobium (Limited)
   • Nitrogen Gas - Nitrates
   • Only Possible with Arch & Prok
   • During Ligtening Nitrogen+Oxygen = nitrogen oxidise - dissolved in rain to ground
   • Nitrogen Fixing using Haber Process
     • Fertilisers contain fixed nitrogen. Haber process = Nitrogen + Hydrogen = Ammonia usually coverted into ammonium nitrate. High Inputs 
   • Fixed Nitrogen Uses
     • Made into AA in the root nodules and transported in Xylem around plant
     • If relying on Nitrogen from soil nitrate taken up via active transport and converted into nitrite then ammonia then amino acids then transported around
     • Sometime either Nitrate from soil or from fixing bacteria is transported to the leves ot be converted into ammonia

2. Ammounification

   • Mineralisation
   • Produces ammonium from dead matter
     • Ammoni in soil is coverted into nitrite - nirates by nitryfiing bacteria NITRIFICATION
   • decomposers
     • Proteins break down nitrogen to amino acids using protese enzymes Break down amino acid and release nitrogen as ammonia 
   • Covert organic nitrogen back into ammounium
   • Produced in urine

3. Nitrification

   • Chemotrophic bateria
     • gain energy by oxidising ammounium to nititresto nitrates
     • exam q
       • explain how the activity of these bacteri affects the growth of plants in the ecosystem increase plant growth, they make nitrate plants need for amino acids, proteins, chlorophyll, dna, new cells, mitosis
   • Covert ammonium in soil - nitrite-nitrate
   • Aerobic condiions - oxidiating
   • Nitrosamus and Nitro bacter
     • Get energy from nitirification Only in Aerated soil ammonia - nitrosamus - nitrite - nitrobacter - nitrate 

4. Denitrifcation

   • Nitates - Nitrogen gas
   • Chemotrophoic
     • recieve energy from converting nitrates in to nitrogen gas 
   • find them in sewage plant, compost heaps, wet soils
   • bring the nitrogen cycle to a full circle