Nitrogen is needed mostly for the synthesis of amino acids and nucleotides. Sources of nitrogen can be obtain from organic as well as inorganic sources, but the whole target is the same; move it into the cell and then change it to amino acids and ammonia. The Inorganic make of nitrogen can also serve as sources of nitrogen. One of the most common compounds utilized is nitrate. Various plants, bacteria and fungi are capable of this assimilatory nitrate reduction. The Nitrate is reduce to nitrite through the enzyme nitrate reductase and nitrite is then reduce to ammonia in a series of two electron transfers by nitrite reductase.