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The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes.
Nitrogen cycle. Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms [1] or entirely within one organism, as in comammox bacteria. The transformation of ammonia to ...
Nitrogen fixation is essential to life on Earth because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds such as amino acids, polypeptides and proteins, nucleoside triphosphates and nucleic acids.
Nitrogen is a fundamental chemical component of amino acids, the molecular building blocks of protein. As such, nitrogen balance may be used as an index of protein metabolism. [1] When more nitrogen is gained than lost by an individual, they are considered to have a positive nitrogen balance and be in a state of overall protein anabolism.
Nitrifying bacteria then convert this ammonium into nitrate by oxidation, which can then be used by plants to create more proteins thus completing the nitrogen cycle. [6] This process is called nitrification. Energy from this oxidation reaction can also be used to synthesize organic compounds in a process called chemosynthesis. [7]
The only major component of most food which contains nitrogen is protein (fat, carbohydrate and dietary fiber do not contain nitrogen). If the amount of nitrogen is multiplied by a factor depending on the kinds of protein expected in the food the total protein can be determined. This value is known as the "crude protein" content.
A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle, the nitrogen cycle and the water cycle. In each cycle, the chemical element or molecule is ...
The conversion of glutamate to glutamine is regulated by glutamine synthetase (GS) and is a key step in nitrogen metabolism. [2] This enzyme is regulated by at least four different mechanisms: 1. Repression and depression due to nitrogen levels; 2. Activation and inactivation due to enzymatic forms (taut and relaxed); 3.