Monosaccharides Essay -- essays research papers

monosaccharose also called SIMPLE SUGAR, any of the basic compounds that serve as the twist blocks of carbohydrates. Monosaccharides atomic number 18 polyhydroxy aldehydes or ket unrivalleds that is, they are molecules with more than one hydroxyl meeting (-OH), and a carbon copyyl free radical (C=O) either at the terminal carbon atom (aldose) or at the second carbon atom (ketose). The carbonylic group combines in aqueous solution with one hydroxyl group to form a cyclic compound (hemi-acetal or hemi-ketal). Monosaccharides are sort by the number of carbon atoms in the molecule trioses have three, tetroses four, pentoses five, hexoses six, and heptoses seven. nearly contain five or six. The most important pentoses take on xylose, shew combined as xylan in woody materials arabinose from coniferous trees ribose, a piece of ribonucleic acidulateds and several vitamins and deoxyribose, a component of deoxyribonucleic acid. Among the most important aldohexoses are glucose, man nose, and brain prick fructose is a ketohexose.Several derivatives of monosaccharides are important. Ascorbic acid (vitamin C) is derived from glucose. Important sugar alcohols (alditols), formed by the reduction of (i.e., addition of hydrogen to) a monosaccharide, include sorbitol (glucitol) from glucose and mannitol from mannose two are used as sweetening agents. Glycosides derived from monosaccharides are widespread in nature, especially in plants. Amino sugars (i.e., sugars in which one or two hydroxyl groups are replaced with an amino group, -NH2) occur as components of glycolipids and in the chitin of arthropods.      carbohydrateClasses of carbohydrates Monosaccharides Sources The most common naturally occurring monosaccharides are D-glucose, D-mannose, D-fructose, and D-galactose among the hexoses, and D-xylose and L-arabinose among the pentoses. In a special sense, D-ribose and 2-deoxy-D-ribose are ubiquitous because they form the carbohydrate compone nt of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), respectively these sugars are prove in all cells as components of nucleic acids. Sources of some of the naturally occurring monosaccharides are listed in Table 2.D-xylose, found in most plants in the form of a polysaccharide called xylan, is prepared from corncobs, cottonseed hulls, or straw by chemical breakdown of xylan. D-galactose, a common portion of both... ...his step, syrup preparations are crystallized to form table sugar. Successive "crops" of saccharose crystals are "harvested," and the later ones are known as brown sugar. The equalizer syrupy material is called either piece of taile final molasses or blackstrap molasses both are used in the preparation of antibiotics, as sweetening agents, and in the production of alcohol by yeast fermentation.Sucrose is formed following photosynthesis in plants by a reaction in which sucrose phosphate origin is formed.The disaccharide trehalose is simil ar in many respects to sucrose but is much less widely distributed. It is composed of two molecules of -D-glucose and is also a nonreducing sugar. Trehalose is present in young mushrooms and in the resurrection plant (Selaginella) it is of considerable biological pursuance because it is also found in the circulating fluid (hemolymph) of many insects. Since trehalose can be converted to a glucose phosphate compound by an enzyme-catalyzed reaction that does not require energy, its function in hemolymph may be to proffer an immediate energy source, a role similar to that of the carbohydrate storehouse forms (i.e., glycogen) found in higher animals.