NITROGEN CYCLE

Nitrogen Cycle  All organisms use nitrogen in DNA and Proteins  Most abundant form element in atmosphere  Forms of Nitrogen:  NH 4 +  NO 3 -  Plants absorb nitrogen while animals eat plants

Nitrogen Fixation  Conversion of gaseous nitrogen to ammonium ions  Bacteria living in soil Bacteria live with roots of plants and form symbiotic relationship with them and convert nitrogen in soil  Lightening causes oxidization of nitrogen gas to nitrate which ends up in the soil  Industry uses pressure to combine nitrogen with fertilizer using iron as a catalyst

Nitrification Denitrification  Converting ammonium to nitrites (nitrosomonas) or nitrites to nitrates (nitrobacter)  Available to be absorbed by plants  Denitrifying bacteria (pseudomonas denitrificans) convert ammonium, nitrate and nitrite ions to nitrogen gas  Decomposition provides nitrogen for plants  More effective than Nitrogen Fixation

Assimilation  Once organisms take in nitrogen, they assimilate more complex molecules  Proteins synthesis turns inorganic nitrogen compounds to complex amino acids and from proteins

Human Relationship  When humans remove plants and animals from earth, they extract from nitrogen cycle  Nitrogen is later lot in sea to human exchange  Artificial fertilizers (Haber Process) and planting leguminous crops containing nitrogen-fixing bacteria add to cycle  Plants enrich soil with nitrogen, but can cause nitrogen gas to pollute air (denitrification)

Nitrogen Cycle Process  e/vis_sim/em05_pg20_nitrogen/em05_pg20_nitro gen.html e/vis_sim/em05_pg20_nitrogen/em05_pg20_nitro gen.html