CH 461 Lecture Notes - Lecture 20: Nitrogen Fixation, Nitrogen Cycle, Chemosynthesis
Document Summary
Just as photosynthesis or chemosynthesis must reduce carbon dioxide in the atmosphere before it can be used in biological reactions, so must biological nitrogen change from elemental n 2 to a 3 level, as in ammonia, nh 3. In terrestrial and aquatic systems, reduced nitrogen is often a limiting nutrient for plant growth. About half of all global nitrogen fixation occurs industrially in a process that requires a metal catalyst at. In contrast, biological nitrogen fixation takes place in a much less extreme environment (about 25 and 1 atmosphere pressure) in the roots of leguminous plants or in bacteria, using enzymatic catalysts. Eventually it returns to the atmosphere as n 2. The overall process is referred to as the nitrogen cycle. Reduced nitrogen is used for the synthesis of cellular components. All organisms can incorporate ammonia nitrogen into amino acids, purine and pyrimidine bases, and so forth, so the level of nh 3 is the most useful for cell metabolism.
