sulfur and nitrogen cycle

• NITROGEN CYCLE


  The cycle of nitrogen through the environment
• Key molecules in the nitrogen cycle

  • amino acids
  • proteins
  • nucleic acid
• Ammonia and ammonium ion

  Won't become useful so they are considered to be toxic
• Conversion of ammonia and ammonium

  They must be converted into nitrite or nitrate, and that is what they will use
• Nitrogen is one of the primary nutrients critical for the survival of all living organisms. It is a necessary component of many biomolecules, including proteins, DNA, and chlorophyll.
• Although nitrogen is very abundant in the atmosphere as dinitrogen gas (N2), it is largely inaccessible in this form to most organisms, only when nitrogen is converted from dinitrogen gas into ammonia (NH) does it become available to primary producers, such as plants.
• Nitrogen fixation


  N2 + 3H2→ 2NH3 (NH4+)
• NH4+


  Ammonia ion
• Nitrogenase


  Enzyme responsible for nitrogen fixation
• Ammonia (NH3) and Ammonium (NH4+) are TOXIC.
• Nitrification


  NH4-→ NO2-→ NO3-
• Nitrosomonas


  Nitrifying bacterium that oxidizes ammonia to nitrite
• Nitrobacter


  Bacterium that converts nitrite into nitrates
• Assimilation


  Nitrate and ammonium transformed into proteins and amino acids
• Plants take up these forms of nitrogen through their roots and incorporate them into plant proteins and nucleic acids.
• Nitrate can be used by the plants as their source of proteins and nucleic acid
• Denitrifying


  NO3->n2
• Excess nitrate with the help of denitrifying bacteria that will convert nitrogen to the atmospheric environment
• Pseudomonas


  Under anaerobic conditions, reduce the amount of fixed nitrogen (as fertilizer) by up to 50%.
• Denitrification


  The process in which nitrate present in soil is reduced to nitrogen
• Ammonification


  NO2 / NO3-→ NH4+(NH3)
• There is some instances that legumes that are dead and what happens is that the nitrates present will be used as fertilizer. Then, it is released to the soil, the plant will grow so when we plant again, the plant will grow
• Through simple decomposition and hydrolysis of the polymers, the organic matter is converted back into inorganic ammonia (ammonification).
• Involves decomposers, and waste products (feces). Take note that this also has nitrogen.
• If the source of the nitrogen is animals then it will undergo ammonification
• Either it will be nitrate and nitrite into ammonia so that it will easier for plants to absorb
• If it will be ammonia, we will go back to the cycle from ammonia to nitrates
• It will come back into nitrification from waste products
• Two sources of terrestrial nitrogen

  • Atmospheric
  • Waste products (of animal) with the help of decomposers
• Nitrogen fixation


  N2 → NH4+
• Some bacteria (cyanobacteria) take the dissolved N, and convert it into ammonium (NH4) through nitrogen fixation.
• Nitrogen will be absorbed by the water and n2 is not useful and must be converted
• The cyanobacteria will be responsible for converting the atmospheric nitro to ammonia
• Nitrification


  NH4+ → NO2^2-or NO3-
• Some of this ammonium can be used directly by phytoplankton, but the majority of it is converted by ammonia-oxidizing bacteria into nitrite (NO2^2-) or by nitrite-oxidizing bacteria into nitrate (NO3 ) through the process of nitrification.
• Nitrate is the main nitrogenous compound utilized by primary producers in the ocean; it is a major nutrient required for photosynthesis.
• Ammonification


  The ammonium taken in by phytoplankton gets passed on to consumer organisms, and then gets returned to the ocean through decomposition of wastes and organic matter as these organisms die and sink into deeper water.
• Phytoplankton will take the ammonium and then it will convert into nitrite and nitrate the phytoplankton will be eaten consumer, then they will also contain ammonium so they will convert into nitrite and nitrate
• Assimilation


  Once converted into ammonium, the organism will now absorb this
• Phytoplanktons Consume the ammonium, nitrite and nitrate