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  2. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    In terms of tissue type, the body may be analyzed into water, fat, connective tissue, muscle, bone, etc. In terms of cell type, the body contains hundreds of different types of cells, but notably, the largest number of cells contained in a human body (though not the largest mass of cells) are not human cells, but bacteria residing in the normal ...

  3. Metabolic pathway - Wikipedia

    en.wikipedia.org/wiki/Metabolic_pathway

    The metabolic pathway in the cell is regulated by covalent or non-covalent modifications. A covalent modification involves an addition or removal of a chemical bond, whereas a non-covalent modification (also known as allosteric regulation) is the binding of the regulator to the enzyme via hydrogen bonds , electrostatic interactions, and Van der ...

  4. Metabolism - Wikipedia

    en.wikipedia.org/wiki/Metabolism

    Metabolism (/ m ə ˈ t æ b ə l ɪ z ə m /, from Greek: μεταβολή metabolē, "change") is the set of life-sustaining chemical reactions in organisms.The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks of proteins, lipids, nucleic acids, and some carbohydrates; and the ...

  5. Steady state (biochemistry) - Wikipedia

    en.wikipedia.org/wiki/Steady_state_(biochemistry)

    In biochemistry, steady state refers to the maintenance of constant internal concentrations of molecules and ions in the cells and organs of living systems. [1] Living organisms remain at a dynamic steady state where their internal composition at both cellular and gross levels are relatively constant, but different from equilibrium concentrations. [1]

  6. Nicotinamide adenine dinucleotide - Wikipedia

    en.wikipedia.org/wiki/Nicotinamide_adenine_di...

    The actual concentration of NAD + in cell cytosol is harder to measure, with recent estimates in animal cells ranging around 0.3 mM, [18] [19] and approximately 1.0 to 2.0 mM in yeast. [20] However, more than 80% of NADH fluorescence in mitochondria is from bound form, so the concentration in solution is much lower.

  7. Cellular respiration - Wikipedia

    en.wikipedia.org/wiki/Cellular_respiration

    Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. The overall reaction occurs in a series of biochemical steps, some of which are redox reactions. Although cellular respiration is technically a combustion reaction , it is an unusual one because of the slow, controlled release of energy from the series ...

  8. Cell biology - Wikipedia

    en.wikipedia.org/wiki/Cell_biology

    Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. [1] [2] All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. [3] Cell biology is the study of the structural and functional ...

  9. Biochemistry - Wikipedia

    en.wikipedia.org/wiki/Biochemistry

    Just six elements—carbon, hydrogen, nitrogen, oxygen, calcium and phosphorus—make up almost 99% of the mass of living cells, including those in the human body (see composition of the human body for a complete list). In addition to the six major elements that compose most of the human body, humans require smaller amounts of possibly 18 more ...