Nitrogen Cycle

DECOMPOSERS are organism that feed on waste from other organisms, or dead organism
     ---> feed saprotrophically so are saprotrophs, i.e they release enzymes on too dead/waste matter which digest material into smaller molecules which are then absorbed into the organisms body where they are stored or respired to release energy
- If this did not happen then energy and valuable nutrients would remian trapped within dead organisms. Micro-organisms, therefore, have a particularly important role to play in the cycling of carbon and nitrogen within ecosystems

- Nirtogen must be fixed
     ---> converted into a more usable form e.g ammonium ions or nitrate ions

- Nitrogen fixation can happen through bacteria
    ---> nodules provide place for Rhizobium bacteria
    ---> leghaemoglobin mops up unwanted O2

- Rhizobium uses nitrogenase (enzyme) that converts N2 in the air to nitrates
       - Rhizobium bacteria invades roots
       - Stimulates nodules to develop
       - Bacteria forms colonies inside nodules
       - Use a nitrogenase enzyme to covert nitrogen gas (N2) into ammonium ions (NH4+)

- Nitrogen is assimilated by animals
      - Animals eat plant proteins
      - These are digested to amino acids
      - Amino acids are re-built into proteins in the animal
      - Nitrogen is returned to the soil when the plant or animal dies or during excretion
---> Excretion = Ammonification

- Denitrification
     ---> In waterlogged soils, nitrates and ammonium ions are in short supply

This animation is an interesting take on the nitrogen cycle (be warned the guys voice gets a little annoying after a while) if you are a more visual learner you may find this useful.....



Why is this important? Well plants and animals need nitrogen...... going back to AS stuff this is......

Amino acids ---> proteins e.g haemoglobin, collagen, antibodies and enzymes

Nucleotide ---> DNA, RNA (mRNA, and tNRA)