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Steroid, any of a class of natural or synthetic organic compounds characterized by a molecular structure of 17 carbon atoms arranged around four rings. Steroids are important in biology, chemistry, and medicine. Learn more about the nomenclature, synthesis, and biological significance of steroids.
Steroid - Numbering, Nomenclature, System: All steroids are related to a characteristic molecular structure composed of 17 carbon atoms—arranged in four rings conventionally denoted by the letters A, B, C, and D—bonded to 28 hydrogen atoms.
Steroid - Hormones, Lipids, Cholesterol: A large group, the sterols, is composed of the common 3-monohydroxy steroids of the cholestane, ergostane, and stigmastane series and their methyl sterol biogenetic precursors: lanosterol, cycloartenol, and certain derivatives of these sterols, such as lophenol. Most sterols have a 3β-hydroxyl group ...
Steroid hormones are secreted by three glands—the adrenal cortex, testes, and ovaries—and by the placenta during pregnancy. Learn more about steroid hormone classification, secretion, and function.
Structure elucidation in the steroid field, as in all areas of organic chemistry, depends heavily on physical methods, particularly nuclear magnetic resonance, infrared spectroscopy, mass spectrometry, and X-ray crystallography.
steroid, Any of a class of natural or synthetic organic compounds with a molecular core, or nucleus, of 17 carbon atoms in a characteristic three-dimensional arrangement of four rings. The configuration of the nucleus, the nature of the groups attached to it, and their positions distinguish different steroids.
Steroid - Biosynthesis, Metabolism, Hormones: In plants and animals, steroids appear to be biosynthesized by similar reactions, beginning with acetic acid, assisted by a type of enzyme. The isoprenoid hydrocarbon called squalene, which occurs widely in nature, is thought to be the starting material from which all steroids are made.
Lipid-derived hormones, known as steroid hormones, are important chemical messengers and include testosterone and estrogens. At an organismal level triglycerides stored in adipose cells serve as energy-storage depots and also provide thermal insulation.
The specific information content of the steroid resides in the character and arrangement of its substituent groups and in other subtle structural modifications. The most generally abundant steroids are sterols, which occur in all tissues of animals, green plants, and fungi such as yeasts.
adrenal hormone. steroid hormone, any of a group of hormones that belong to the class of chemical compounds known as steroids; they are secreted by three “steroid glands”—the adrenal cortex, testes, and ovaries —and during pregnancy by the placenta. All steroid hormones are derived from cholesterol.