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  2. Nitrogen fixation - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_fixation

    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]

  3. Bone resorption - Wikipedia

    en.wikipedia.org/wiki/Bone_resorption

    Bone is resorbed by osteoclasts, and is deposited by osteoblasts in a process called ossification. [6] Osteocyte activity plays a key role in this process. Conditions that result in a decrease in bone mass can either be caused by an increase in resorption or by a decrease in ossification. During childhood, bone formation exceeds resorption.

  4. Nitrogenase - Wikipedia

    en.wikipedia.org/wiki/Nitrogenase

    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 ...

  5. Nif gene - Wikipedia

    en.wikipedia.org/wiki/Nif_gene

    The nif genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen into a form of nitrogen available to living organisms. The primary enzyme encoded by the nif genes is the nitrogenase complex which is in charge of converting atmospheric nitrogen (N 2) to other nitrogen forms such as ammonia which the organism can use for various purposes.

  6. Abiological nitrogen fixation using homogeneous catalysts

    en.wikipedia.org/wiki/Abiological_nitrogen...

    Abiological nitrogen fixation describes chemical processes that fix (react with) N 2, usually with the goal of generating ammonia. The dominant technology for abiological nitrogen fixation is the Haber process, which uses iron-based heterogeneous catalysts and H 2 to convert N 2 to NH 3. This article focuses on homogeneous (soluble) catalysts ...

  7. Bone remodeling - Wikipedia

    en.wikipedia.org/wiki/Bone_remodeling

    Bone tissue is removed by osteoclasts, and then new bone tissue is formed by osteoblasts. Both processes utilize cytokine (TGF-β, IGF) signalling.In osteology, bone remodeling or bone metabolism is a lifelong process where mature bone tissue is removed from the skeleton (a process called bone resorption) and new bone tissue is formed (a process called ossification or new bone formation).

  8. Dissimilatory nitrate reduction to ammonium - Wikipedia

    en.wikipedia.org/wiki/Dissimilatory_nitrate...

    Dissimilatory nitrate reduction to ammonium is more common in prokaryotes but may also occur in eukaryotic microorganisms. [3] [4] [5] DNRA is a component of the terrestrial and oceanic nitrogen cycle. Unlike denitrification, it acts to conserve bioavailable nitrogen in the system, producing soluble ammonium rather than unreactive nitrogen gas ...

  9. Heterocyst - Wikipedia

    en.wikipedia.org/wiki/Heterocyst

    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]