2025年1月13日 · A steroid is 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.

2025年1月13日 · 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.

2025年1月13日 · The molecular structures of metabolites of cholesterol form an evolutionary series from the bile alcohols, such as myxinol and scymnol of the elasmobranch fishes (e.g., sharks and rays) and the related alcohols of some bony fishes and frogs, through the 5β-cholestanoic acids of crocodiles and alligators, to the 5β-cholanoic acids of the birds ...

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.

2025年2月21日 · Chemically, cholesterol is an organic compound belonging to the steroid family; its molecular formula is C 27 H 46 O. In its pure state it is a white, crystalline substance that is odourless and tasteless.

2025年1月4日 · The characteristic feature of each of these three important molecules is four rigidly fused carbon rings forming the steroid nucleus and a hydroxyl (OH) group attached to the first ring. One molecule is distinguished from another by the positions of the carbon-carbon double bonds and by the structure of the hydrocarbon side chain on the fourth ...

2025年2月13日 · 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.

Isoprenoid - Terpenes, Steroids, Carotenoids: The problems in molecular structure presented by the isoprenoids have challenged the imagination and skill of organic chemists since the latter part of the 19th century.

2025年1月13日 · 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.

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.