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7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D 3 in the skin, therefore functioning as provitamin -D 3. The presence of this compound in human skin enables humans to manufacture vitamin D 3 (cholecalciferol). Upon exposure to ultraviolet UV-B rays ...
Cholesterol is the principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. [3][4] Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membranes.
About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are ...
Chirality (chemistry) Two enantiomers of a generic amino acid that are chiral. (S)-Alanine (left) and (R)-alanine (right) in zwitterionic form at neutral pH. In chemistry, a molecule or ion is called chiral (/ ˈkaɪrəl /) if it cannot be superposed on its mirror image by any combination of rotations, translations, and some conformational changes.
Chirality(/kaɪˈrælɪti/) is a property of asymmetryimportant in several branches of science. The word chiralityis derived from the Greekχείρ(kheir), "hand", a familiar chiral object. An object or a system is chiralif it is distinguishable from its mirror image; that is, it cannot be superposed(not to be confused with superimposed) onto it.
These include sphingosine-1-phosphate, a sphingolipid derived from ceramide that is a potent messenger molecule involved in regulating calcium mobilization, [71] cell growth, and apoptosis; [72] diacylglycerol and the phosphatidylinositol phosphates (PIPs), involved in calcium-mediated activation of protein kinase C; [73] the prostaglandins ...
Structures. Muscles. See also. v. t. e. This article contains a list of organs in the human body. It is widely believed that there are 79 organs (this number goes up if you count each bone and muscle as an organ on their own, which is becoming a more common practice [1][2]); however, there is no universal standard definition of what constitutes ...
Chiral media. Chirality with hands and two enantiomers of a generic amino acid. The direction of current flow and induced magnetic flux follow a "handness" relationship. The term chiral / ˈkaɪrəl / describes an object, especially a molecule, which has or produces a non-superposable mirror image of itself. In chemistry, such a molecule is ...