Nitrogen Cycle
Nitrogen cycle & Greenhouse Gases
The nitrogen cycle is an important chemical cycle which occurs in the ecosystem. The nitrogen cycle begins when atmospheric N2 is transformed by organisms to NH4. This NH4 is than converted into nitrite which is later converted into nitrate, and the process further repeats itself. The nitrogen cycle is important because it results in important compounds being produced which are essential for proper growth of plants and other organisms.
Nitrogen cycle processes
Nitrogen fixation Nitrogen Mineralization Nitrification occurs in aerobic conditions Denitrification- occurs in anaerobic conditions
Nitrogen fixation
Atmospheric nitrogen (N2) is abundant, but unavailable for biological activity due to the high energy required to break the triple bond. In nitrogen fixation, atmospheric nitrogen is reduced to biologically useful ammonia (NH3) by the activity of prokaryotes utilizing a nitrogenase.
Chemistry
The reaction catalyzed by nitrogenase is N2 + 8H+ + 8e- ---> 2NH3 + H2. Ammonia produced in this way is rapidly protonated to NH4+. Nitrogenases are irreversibly inhibited by exposure to O2, and thus organisms must take steps to prevent this. Some organisms, such as azotobacter protect their nitrogenases with a thick capsule that slows oxygen diffusion. Others, such as the cyanobacteria nostoc form special cells with thick cell walls to exclude oxygen, allowing the cell to provide fixed nitrogen to its neighbors. Alternative nitrogenases do exist that are not deactivated by oxygen, but they are found in a relatively small number of organisms.
Ecology
Nitrogen fixed by prokaryotes constitutes the vast majority of all biologically active nitrogen on the planet. Nitrogen-fixers may be aerobic or anaerobic, and may be free-living or in a symbiotic relationship with a plant.
Nitrogen Mineralization
Subsection 2a
Subsection 2b
Atmospheric N2 into NH4+
Nitrification
Subsection 3a
Subsection 3b
NH4+ to NO3-
Denitrification
Subsection 4a
Subsection 4b
NO3- to Atmospheric N2, happens in anaerobic conditions
Key Microorganisms in Nitrogen cycle
Bacteria involved- nitraosomas, nitrobacter, e.g. Nitrobacter hamburgensis, Nitrobacter winogradskyi,are key players in the nitrogen cycle
Identify and describe some microorganisms involved. Do they already have their own microbewiki pages? Add links. Create at least one page for a microbe relevant to your topic. Template will appear soon.
Greenhouse gases
Topic of your choice.
Nitrous oxide or "laughing gas" is the form of nitrogen that is a green house gas. Along with carbon dioxide, ozone, methane, water vapor, and halocarbons, nitrous oxide causes the blanket of air surrounding the earth to thicken; thus warming up the earth itself. This phenomenon has been dubbed "Global Warming" and understanding it's causes is key to preventing the mass destruction that will happen if green house gases remain unchecked. (The Environmental Literacy Council)
Current Research
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The Center of Limnology is currently studying the rise in organic nitrogen availability to microbes. Their findings may lead to an analysis of the consequences of anthropogenic nitrogen enrichment watersheds. To learn more visit their website at http://cires.colorado.edu/limnology/research/
References
Edited by student of Kate Scow
