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Fructose (/ ˈ f r ʌ k t oʊ s,-oʊ z /), or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose.It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed by the gut directly into the blood of the portal vein during digestion.
n with n between 3 and 7 (deoxyribose being an exception). Glucose has the molecular formula C 6 H 12 O 6. The names of typical sugars end with -ose, as in "glucose" and "fructose". Sometimes such words may also refer to any types of carbohydrates soluble in water. The acyclic mono- and disaccharides contain either aldehyde groups or ketone groups.
Unlike glucose, fructose is not an insulin secretagogue, and can in fact lower circulating insulin. [4] In addition to the liver, fructose is metabolized in the intestines, testis, kidney, skeletal muscle, fat tissue and brain, [5] [6] but it is not transported into cells via insulin-sensitive pathways (insulin regulated transporters GLUT1 and ...
For example, milk sugar (lactose) is a disaccharide made by condensation of one molecule of each of the monosaccharides glucose and galactose, whereas the disaccharide sucrose in sugar cane and sugar beet, is a condensation product of glucose and fructose.
Oligosaccharides of glucose combined with other sugars serve as important energy stores. These include lactose, the predominant sugar in milk, which is a glucose-galactose disaccharide, and sucrose, another disaccharide which is composed of glucose and fructose. Glucose is also added onto certain proteins and lipids in a process called ...
Likewise, gastric acidity converts sucrose to glucose and fructose during digestion, the bond between them being an acetal bond which can be broken by an acid. Given (higher) heats of combustion of 1349.6 kcal/mol for sucrose, 673.0 for glucose, and 675.6 for fructose, [ 13 ] hydrolysis releases about 1.0 kcal (4.2 kJ) per mole of sucrose, or ...
In 1897, an unfermentable product obtained by treatment of fructose with bases, in particular lead(II) hydroxide, was given the name glutose, a portmanteau of glucose and fructose, and was claimed to be a 3-ketohexose. [12] [13] However, subsequent studies showed that the substance was a mixture of various other compounds. [13] [14]
Conversion between the furanose, acyclic, and pyranose forms of D-glucose Pyranose forms of some pentose sugars Pyranose forms of some hexose sugars. For many monosaccharides (including glucose), the cyclic forms predominate, in the solid state and in solutions, and therefore the same name commonly is used for the open- and closed-chain isomers.