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  2. Biological thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Biological_thermodynamics

    In animals, the processes of alternating cycles of biochemical reactions of ATP synthesis and cleavage occur automatically. Moreover, the processes of alternating cycles of biochemical reactions at the levels of organs, systems and the whole organism, for example, respiration , heart contractions and others occur with different periods and ...

  3. Transmethylation - Wikipedia

    en.wikipedia.org/wiki/Transmethylation

    Transmethylation is a biologically important organic chemical reaction in which a methyl group is transferred from one compound to another. An example of transmethylation is the recovery of methionine from homocysteine. In order to sustain sufficient reaction rates during metabolic stress, this reaction requires adequate levels of vitamin B 12 ...

  4. Biogeochemical cycle - Wikipedia

    en.wikipedia.org/wiki/Biogeochemical_cycle

    A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle, the nitrogen cycle and the water cycle. In each cycle, the chemical element or molecule is ...

  5. Reverse Krebs cycle - Wikipedia

    en.wikipedia.org/wiki/Reverse_Krebs_cycle

    The Reductive/Reverse TCA Cycle (rTCA cycle). Shown are all of the reactants, intermediates and products for this cycle. The reverse Krebs cycle (also known as the reverse tricarboxylic acid cycle, the reverse TCA cycle, or the reverse citric acid cycle, or the reductive tricarboxylic acid cycle, or the reductive TCA cycle) is a sequence of chemical reactions that are used by some bacteria and ...

  6. Urea cycle - Wikipedia

    en.wikipedia.org/wiki/Urea_cycle

    This cycle was the first metabolic cycle to be discovered by Hans Krebs and Kurt Henseleit in 1932, [2] [3] [4] five years before the discovery of the TCA cycle. The urea cycle was described in more detail later on by Ratner and Cohen. The urea cycle takes place primarily in the liver and, to a lesser extent, in the kidneys.

  7. Protein metabolism - Wikipedia

    en.wikipedia.org/wiki/Protein_metabolism

    The process of bind an amino acid to a tRNA is known as tRNA charging. Here, the enzyme aminoacyl-tRNA-synthetase catalyzes two reactions. In the first one, it attaches an AMP molecule (cleaved from ATP) to the amino acid. The second reaction cleaves the aminoacyl-AMP producing the energy to join the amino acid to the tRNA molecule. [14]

  8. File:Bromine Biogeochemical Cycle .pdf - Wikipedia

    en.wikipedia.org/wiki/File:Bromine...

    English: This figure illustrates the anthropogenic and natural sources of bromine in the atmosphere. The major sources include sea spray, salt lakes, marshes, volcanos, anthropogenic sources, and the least input is the polar regions.

  9. Q cycle - Wikipedia

    en.wikipedia.org/wiki/Q_cycle

    The Q cycle (named for quinol) describes a series of sequential oxidation and reduction of the lipophilic electron carrier Coenzyme Q (CoQ) between the ubiquinol and ubiquinone forms. These reactions can result in the net movement of protons across a lipid bilayer (in the case of the mitochondria, the inner mitochondrial membrane ).