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Nitrogen fixation is a chemical process by which molecular dinitrogen (N 2) is converted into ammonia (NH 3). [1] It occurs both biologically and abiologically in chemical industries. Biological nitrogen fixation or diazotrophy is catalyzed by enzymes called nitrogenases. [2]
Nitrogenase is the enzyme that catalyzes the conversion of atmospheric nitrogen molecules N 2 into ammonia (NH 3) through the process known as nitrogen fixation. Because it contains iron and molybdenum, the cofactor is called FeMoco. Its stoichiometry is Fe 7 MoS 9 C.
Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc, Cylindrospermum, and Anabaena. [1] They fix nitrogen from dinitrogen (N 2) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis. [2]
Nitrogenase is an enzyme responsible for catalyzing nitrogen fixation, which is the reduction of nitrogen (N 2) to ammonia (NH 3) and a process vital to sustaining life on Earth. [9] There are three types of nitrogenase found in various nitrogen-fixing bacteria: molybdenum (Mo) nitrogenase, vanadium (V) nitrogenase , and iron-only (Fe ...
Fixation of tissue is done for several reasons. One reason is to kill the tissue so that postmortem decay (autolysis and putrefaction) is prevented. [1] Fixation preserves biological material (tissue or cells) as close to its natural state as possible in the process of preparing tissue for examination. To achieve this, several conditions ...
Photosynthesis, a process whereby carbon dioxide and water are transformed into a number of organic molecules in plant cells.; Nitrogen fixation from the soil into organic molecules by symbiotic bacteria which live in the roots of certain plants, such as Leguminosae.
Nitrogen enters the ocean through precipitation, runoff, or as N 2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N 2 so it must undergo nitrogen fixation which is performed predominantly by cyanobacteria. [82] Without supplies of fixed nitrogen entering the marine cycle, the fixed nitrogen would be used up in about 2000 ...
In developing bones, ossification commences within the primary ossification center located in the center of the diaphysis (bone shaft), [5] where the following changes occur: The perichondrium surrounding the cartilage model transforms into the periosteum. During this transformation, special cells within the perichondrium switch gears.