Nitrogen cycle

Nitrogen cycle

     Nitrogen gas makes up 78% of our atmosphere and nitrogen is also a part of many molecules essential to life like protein nucleic acid (DNA and RNA) and some vitamins.

     Nitrogen is found in other biologicall -y important compounds such as alkaloids and urea too. Nitrogen is thus an essential nutrient from all life forms and life would be simple if all these life-forms could use the atmospheric nitrogen directly. However, other than a cube from of bacteria life forms are not able to convert the comparatively inert nitrogen molecules into form like nitrates and nitrites which can be taken up and used to make require molecules.

   These  nitrogen fixing bacteria may be free living or be associated with some spices of dicot plants. Most commonly the nitrogen fixing bacteria are found in the root of legumes (generally the plants which give us pulses)in special structures called root  nodules.

    Other than this bacteria,the only other manner is which the nitrogen molecules is converted to nitrate and nitrite is by the physical process.

   During lightning,the high temperatures and pressures create in the year convert nitrogen into oxide of nitrogen. These oxides dissolved in water to give nitric and nitrous acid and fall on land along with  these are there in utilised by various life forms. 

     What happens to the nitrogen once it is converted into forms that can be taken up and used to make nitrogen containing molecules?

   Plants generally take up nitrites and nitrates and convert them into amino acids which are used to make proteins. Some other biological pathway are used to make the other complex compounds containing nitrogen and other complex compounds .

These protein and other complex compoundare subsequently  consumed by animals. Once the animals for the plant dies,other bacteria in the soil convert the various compound of nitrogen back into nitrites and nitrates.

A different type of bacteria converts the nitrites and nitrates into elemental nitrogen does there is the nitrogen cycle in nature in which nitrogen pass from this element from in the atmosphere into simple molecules in the soil and water which get converted to more complex molecules in living being and back again to the simple nitrogen molecules in the atmosphere.