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sugar

(Encyclopedia)sugar, compound of carbon, hydrogen, and oxygen belonging to a class of substances called carbohydrates. Sugars fall into three groups: the monosaccharides, disaccharides, and trisaccharides. The mono...

fossil

(Encyclopedia)fossil, remains or imprints of plants or animals preserved from prehistoric times by the operation of natural conditions. Fossils are found in sedimentary rock, asphalt deposits, and coal and sometime...

insulin

(Encyclopedia)insulin, hormone secreted by the β cells of the islets of Langerhans, specific groups of cells in the pancreas. Insufficiency of insulin in the body results in diabetes. Insulin was one of the first ...

ligand

(Encyclopedia)ligand lĭgˈənd [key], charged or uncharged molecule with one or more unshared pairs of electrons that can attach to a central metallic atom or ion to form an aggregate known as a complex ion (see c...

metabolism

(Encyclopedia)metabolism, sum of all biochemical processes involved in life. Two subcategories of metabolism are anabolism, the building up of complex organic molecules from simpler precursors, and catabolism, the ...

micromechanics

(Encyclopedia)micromechanics, the combination of minuscule electrical and mechanical components in a single device less than 1 mm across, such as a valve or a motor. Although micromechanical production processes an...

sulfa drug

(Encyclopedia)sulfa drug, any of a class of synthetic chemical substances derived from sulfanilamide, or para-aminobenzenesulfonamide. Sulfa drugs are used to treat bacterial infections, although they have largely ...

peptide

(Encyclopedia)peptide, organic compound composed of amino acids linked together chemically by peptide bonds. The peptide bond always involves a single covalent link between the α-carboxyl (oxygen-bearing carbon) o...

benzene

(Encyclopedia)benzene bĕnˈzēn, bĕnzēnˈ [key], colorless, flammable, toxic liquid with a pleasant aromatic odor. It boils at 80.1℃ and solidifies at 5.5℃. Benzene is a hydrocarbon, with formula C6H6. The s...

thymine

(Encyclopedia)thymine thīˈmēn [key], organic base of the pyrimidine family. Thymine was the first pyrimidine to be purified from a natural source, having been isolated from calf thymus and beef spleen in 1893–...