Nitrogen Cycle
Nitrogen is required for the manufacturing of all amino acids and nucleic acids; however, the average organism cannot use atmospheric nitrogen for these tasks and as a result is dependent on the nitrogen cycle as a source for its usable nitrogen. The nitrogen cycle begins with nitrogen stored in the atmosphere as N2 or nitrogen stored in the soil as ammonium (NH4+), ammonia (NH3), nitrite (NO2-), or nitrate (NO3). Nitrogen is assimilated into living organisms through three stages: nitrogen fixation, nitrification, and plant metabolism. Nitrogen fixation is a process which occurs in prokaryotes in which N2 is converted to (NH4+). Atmospheric nitrogen can also undergo nitrogen fixation by lighting and UV radiation and become NO3-. Following nitrogen fixation, nitrification occurs. During nitrification, ammonia is converted into nitrite, and nitrite is converted into nitrate. Nitrification occurs in various bacteria. In the final stage, plants absorb ammonia and nitrate and incorporate it into their metabolic pathways. Once the nitrogen has entered the plant metabolic pathway, it may be transferred to animals when the plant is eaten. Nitrogen is released back into the cycle when denitrifying bacteria convert NO3- into N2 in the process of denitrification, when detritivorous bacteria convert organic compounds back into ammonia in the process of ammonification, or when animals excrete ammonia, urea, or uric acid.
A lot of environmental problems are caused by the disruption of the nitrogen cycle by human activity, some of the problems caused range from the production of troposphere (lower atmospheric) smog to the perturbation of stratospheric ozone and contamination of ground water. An example of one of the problems caused is the formation of greenhouse gas. Like carbon dioxide and water vapor greenhouse gas traps heat near the earth’s surface and destroys the stratospheric ozone. Once that occurs nitrous oxide in the earth’s atmosphere is broken down by UV light into nitrogen dioxide and nitric oxide. These two products can reduce the ozone. Nitrogen oxides can be changed back into nitrates and nitrite compounds and recycled back into the earth’s surface.
Nitrogen is required for the manufacturing of all amino acids and nucleic acids; however, the average organism cannot use atmospheric nitrogen for these tasks and as a result is dependent on the nitrogen cycle as a source for its usable nitrogen. The nitrogen cycle begins with nitrogen stored in the atmosphere as N2 or nitrogen stored in the soil as ammonium (NH4+), ammonia (NH3), nitrite (NO2-), or nitrate (NO3). Nitrogen is assimilated into living organisms through three stages: nitrogen fixation, nitrification, and plant metabolism. Nitrogen fixation is a process which occurs in prokaryotes in which N2 is converted to (NH4+). Atmospheric nitrogen can also undergo nitrogen fixation by lighting and UV radiation and become NO3-. Following nitrogen fixation, nitrification occurs. During nitrification, ammonia is converted into nitrite, and nitrite is converted into nitrate. Nitrification occurs in various bacteria. In the final stage, plants absorb ammonia and nitrate and incorporate it into their metabolic pathways. Once the nitrogen has entered the plant metabolic pathway, it may be transferred to animals when the plant is eaten. Nitrogen is released back into the cycle when denitrifying bacteria convert NO3- into N2 in the process of denitrification, when detritivorous bacteria convert organic compounds back into ammonia in the process of ammonification, or when animals excrete ammonia, urea, or uric acid.
A lot of environmental problems are caused by the disruption of the nitrogen cycle by human activity, some of the problems caused range from the production of troposphere (lower atmospheric) smog to the perturbation of stratospheric ozone and contamination of ground water. An example of one of the problems caused is the formation of greenhouse gas. Like carbon dioxide and water vapor greenhouse gas traps heat near the earth’s surface and destroys the stratospheric ozone. Once that occurs nitrous oxide in the earth’s atmosphere is broken down by UV light into nitrogen dioxide and nitric oxide. These two products can reduce the ozone. Nitrogen oxides can be changed back into nitrates and nitrite compounds and recycled back into the earth’s surface.
