nitrogen cycle

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Related to Nitrogen metabolism: nitrogen fixation

ni·tro·gen cy·cle

the series of events in which the nitrogen of the atmosphere is fixed, thus made available for plant and animal life, and is then returned to the atmosphere: nitrifying bacteria convert N2 and O2 to NO2- and NO3-, the latter being absorbed by plants and converted to protein; if plants decay, the nitrogen is in part given up to the atmosphere and the remainder is converted by microorganisms to ammonia, nitrites, and nitrates; if the plants are eaten, the animals' excreta or bacterial decay return the nitrogen to the soil and air.
Farlex Partner Medical Dictionary © Farlex 2012

nitrogen cycle

n.
The circulation of nitrogen in nature, consisting of a cycle of chemical reactions in which nitrogen from the atmosphere is fixed in compounds in soil or water, assimilated by plants and animals, released to the soil and water through decomposition, and returned to the atmosphere through denitrification.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

ni·tro·gen cy·cle

(nī'trŏ-jĕn sī'kĕl)
The series of events in which the nitrogen of the atmosphere is fixed, thus made available for plant and animal life, and is then returned to the atmosphere: nitrifying bacteria convert N2 and O2 to NO2- and NO3-, the latter being absorbed by plants and converted to protein; if plants decay, the nitrogen is in part given up to the atmosphere and the remainder is converted by microorganisms to ammonia, nitrites, and nitrates; if the plants are eaten, the animals' excreta or bacterial decay return the nitrogen to the soil and air.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
Nitrogen cycleclick for a larger image
Fig. 229 Nitrogen cycle .

nitrogen cycle

the circulation of nitrogen in the environment as a result of the activity of living organisms. 80% of the atmosphere is made up of nitrogen and this is maintained by the balancing action of the cycle.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
In the present study, we compared the expression of genes related to nitrogen metabolism between a low-nitrogen-tolerant barley cultivar BI-04 and a low-nitrogen-sensitive barley cultivar BI-45 under low-nitrogen stress and found that HvNiR1, HvGS2, and HvGLU2 were induced in shoots of BI-04, while HvASN1 was reduced in both cultivars, and disappeared only in BI-45.
Yang, "Inhibitory effects of enzymes on nitrogen metabolism at mature stage and quality of cured tobacco leaves," Journal of Tobacco Science Technology, vol.
The micronutrient MnS[O.sub.4] is an enzyme activator and essential for carbohydrate and nitrogen metabolism. It also helps in the assimilation of Carbon dioxide in photosynthesis and is also involve in uptake of Iron.
Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage.
Effect of dietary level of rumen- degraded protein on production and nitrogen metabolism in lactating dairy cows.
We tested he availability of enzymes involved for hydrolysis of the plant wall is tested (cellulose, pectinase), for the same for the enzymes related the nodulation process (pectinase) and nitrogen metabolism (urease, nitrate reductase).
Considering the coupling of carbon and nitrogen metabolism, as demonstrated by Turpin (1991), the availability of carbon should make the assimilation of nitrogen faster, supplying cells with carbon for amino acid synthesis.
The TCA cycle and pyruvate metabolism are important for interaction between carbon and nitrogen metabolism. Detailed analysis of their regulatory mechanisms is valuable in understanding the biology of metabolism of cyanobacteria, in biotechnological applications for producing valuable products [35], and in environmental microbiology for avoiding water pollution [36].
Glycine also is seen to participate in glycine, serine, and threonine metabolism which increases in colon cancer and is part of nitrogen metabolism [34].
The nitrogen metabolism and enzymology are related to the selection of high yielding crops.
The topics include water, enzymes, metabolism and energy, photosynthesis, and nitrogen metabolism.