By Clara Martín, Emilio Papastergiou, Mariona Martínez, Olivia Doyhambehere and Sandro Iossa 10/10/2011 9A Biology

 Sandro - What is Nitrogen - The Importance of Nitrogen  Emilio - The Nitrogen Cycle - Nitrogen Fixation  Mariona - Conversion of Nitrogen - Assimilation - Ammonification  Olivia - Nitrification - Denitrification - Anaeorobic Ammonium Oxidation  Clara - Humans and the Nitrogen Cycle

 Nitrogen is a chemical element which is mostly known by it’s importance for organisms. Nitrogen is found everywhere.  In the periodic table, nitrogen is the lightest of the nitrogen group of chemical elements. It’s atomic number is 7 and it is identified with the symbol N. It lacks of three electrons, therefore forms strong bonds with other elements. Sandro

 Nitrogen is around four fifth’s of the Earth’s atmosphere. The majority of animals can’t use nitrogen as something physical, but they do take advantage of nitrogen when it is in nucleic and amino acids. It is the seventh most abundant in the entire universe. Plants need nitrogen in order to feed/nitrate themselves. Everything they consume includes nitrogen in several different forms. Sandro

 Cycle vital for organisms. Nitrogen transfer to numerous forms between organisms and atmosphere. Soil bacteria play a vital role in the cycle.  Ion atom: more protons (+) than electrons (-) or vice versa. Ion molecule: total negative or positive charge.  Nitrogen gas (N 2 ) ammonia (NH 3 ), ammonium (NH 4 + ), nitrite (NO 2 - ) and nitrate (NO 3 - ). 1) Nitrogen gas in atmosphere 2) Bacteria cause Nitrogen Fixation and Ammonification 3) Nitrogen in food chain (Assimilation) 4) a. Ammonium to nitrite to nitrate (Nitrification) b. Ammonium and nitrite nitrogen gas (Anaerobic ammonium oxidation) 5) Nitrate to nitrogen gas in atmosphere (Denitrification)

 Important process in Nitrogen Cycle.  Converts nitrogen gas to ammonia (N 2 +3 H 2 2 NH 3 ). - Biotic: a. Enzymes of soil bacteria create ammonia. Symbiotic relationship of bacteria with plants. - Abiotic: a. Haber Process used to create fertilizers and explosives. b. Lightning reacting and creating ammonia from nitrogen gas.

 Four ways to convert atmospheric nitrogen gas N 2 into some different chemically reactive forms: -Biological fixation: some free-living bacteria and some symbiotic bacteria are able to fix nitrogen as an organic nitrogen. - Industrial N-fixation : Under great pressure, with the use of an iron catalyst, atmospheric nitrogen and hydrogen can be combined to form ammonia (NH 3 ). -Other processes : the formation of NO (nitric oxide) from N 2 and O 2 caused by the photons and most importantly lightning, can fix nitrogen. - Combustion of fossil fuels : automobile engines and thermal power plants, release various nitrogen oxides.

Ammonium and nitrate ions are the to ways that the plants get nitrogen from the soil, by absorption of their roots. When nitrate is absorbed:  First it is reduced into nitrite ions.  Then ammonium ions are formed for the incorporation into:  Amino acids  Nuclei acids  chlorophyll

 Is the result of the breakdown of organic matter such as dead animals and plants or waste materials. This breakdown is accomplished by scores of microorganisms which utilize dead organic material for energy and produce ammonia and related compounds.  Ammonification classically occurs in the soil, in an aerobic environment which gives the bacteria and other microorganisms oxygen to work with.  GS: Gln Synthetase  GOGAT: Glu 2-oxoglutarate aminotransferase  GDH: Glu Dehydrogenase

The biological process in which ammonia(NH3) losses electrons through oxidation and nitrites form into nitrates. Nitrite ions are chemical compounds that form into nitrates through oxidation. Nitrate ions are the conjugate base of nitric acid. Nitrite atoms are nitrites that oxide into nitrites. Nitrification has three steps.

Denitrification is the process that reduces nitrates ultimately forming them into molecular nitrogen. Denitrifying bacteria are bacteria that reduce the amount of nitrates or nitrites and turn them into nitrogen containing gases. It can occur both in soil and marine ecosystems, and it only occurs in areas where there is little or no oxygen(aerobic conditions).

 This is the biological process in which nitrite ions and ammonium are converted into nitrogen gas. This process occurs in many aquatic systems.  The anammox bacteria use nitrite as electron acceptors to produce nitrogen gas, in order to oxidize ammonia.

 The dumping of untreated sewage causes large amounts of nitrogenous waste to accumulate in an ecosystem, causing eutrophication.  The saturation of nitrogen produces red tides.  Burning fossil fuels and wood contributes to a large amount of nitric oxide (NO) in the atmosphere.

 Nitrous oxide (N2O), or laughing gas, is significantly contributing to global warming.

 The use of inorganic fertilizers and overharvesting legumes also unstabilizes an ecosystem.  About 500kg per hectare of nitrogen- based fertilizers are used every year. This is more than the ecosystem can handle, so some of this fertilizer seeps into groundwater or surface rivers and streams.

   