Biomolecules nitrogen fixation

In addition to being important in industry, transition metal ions play a vital role in living organisms. For example, complexes of iron provide for the transport and storage of oxygen, molybdenum and iron compounds are catalysts in nitrogen fixation, zinc is found in more than 150 biomolecules in humans, copper and iron play a crucial role in the respiratory cycle, and cobalt is found in essential biomolecules such as vitamin Bi2-... 

Abont 30 million tons of HNO3 are produced this way annually. Nitric acid is converted to nitrate salts in the soil. These nutrients are taken up by plants, which in turn are ingested by animals. Animals nse the nutrients from plants to make proteins and other essential biomolecules. Denitrification reverses nitrogen fixation to complete the cycle. For example, certain anaerobic organisms decompose animal wastes as well as dead plants and animals to prodnce free molecular nitrogen from nitrates. 

Nitrogen (N) is a component of many biomolecules, especially of proteins and nucleic acids. Molecular N is reduced by certain free-living and symbiotic microorganisms (see Nitrogen fixation) to ammonia, which is the first and final product of nitrogen metabolism. 

The nitrogen in amino acids, purines, pyrimidines, and other biomolecules ultimately comes from atmospheric nitrogen, Nj. The biosynthetic process starts with the reduction of N2 to NH (ammonia), a process called fixation. The extremely strong N —N bond, which has a bond energy of 940 kjmol (225 kcal moP ), is highly resistant to chemical attack... 

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