Monosaccharide unit

Lactose is a disacchande constituting 2-6% of milk and is known as milk sugar It differs from maltose and cellobiose m that only one of its monosaccharide units is D glucose The other monosaccharide unit the one that contributes its anomeric carbon to the glycoside bond is d galactose Like cellobiose lactose is a (3 glycoside... 

Disaccharide (Sections 25 1 and 25 14) A carbohydrate that yields two monosaccharide units (which may be the same or different) on hydrolysis... 

Considers only the basic monosaccharide units. A derivatized monosaccharide unit, such as a D-galactopyranosyl 6-sulfate unit, is not considered as a unit separate from a D-galactopyranosyl unit, for example. 

An important characterization parameter for ceUulose ethers, in addition to the chemical nature of the substituent, is the extent of substitution. As the Haworth representation of the ceUulose polymer shows, it is a linear, unbranched polysaccharide composed of glucopyranose (anhydroglucose) monosaccharide units linked through thek 1,4 positions by the P anomeric configuration. 

Sections Disaccharides are carbohydrates in which two monosaccharides are 25.14-25.15 joined by a glycoside bond. Polysaccharides have many monosaccharide units connected through glycosidic linkages. Complete hydrolysis of disaccharides and polysaccharides cleaves the glycoside bonds, yielding the free monosaccharide components. 

Storage polysaccharides are an important carbohydrate form in plants and animals. It seems likely that organisms store carbohydrates in the form of polysaccharides rather than as monosaccharides to lower the osmotic pressure of the sugar reserves. Because osmotic pressures depend only on numbers of molecules, the osmotic pressure is greatly reduced by formation of a few polysaccharide molecules out of thousands (or even millions) of monosaccharide units. 

If d carbohydrate already contains a nitro group, the nitro-bearing carbon atom can become the nucleophilic center for the conphng of two monosaccharide units fsee Section 3 2 2 Snami and coworkers have used this method for the synthesis of andbiodcs bearing sugars " A typical example is presented in Eq 3 63 "... 

Amino sugars, such as o-glucosamine, have an OH group leplaced by an -NH2. The N-acetyl amide derived from o-glucosamine is the monosaccharide unit from which chitm, the hard crust that protects insects and shellfish, is made. Still otheramino sugars are found in antibiotics such as streptomycin and gentamicin. 

Disaccharides, which are dimers farmed when two monosaccharide units combine with the elimination of H20. The monosaccharides may be the same (two glucose units in maltose) or different (a glucose and fructose unit in sucrose). 

Polysaccharides, which are condensation polymers containing from several hundred to several thousand monosaccharide units. Cellulose and starch are the most common polysaccharides. 

A disaccharide is a compound in which two monosaccharide units are joined by a... 

Numbering of monosaccharide units, if desired, should proceed from right to left. 

This is the form employed by the carbohydrate databank CarbBank, and is preferred for most purposes. Each symbol for a monosaccharide unit is preceded by the anomeric descriptor and the configuration symbol. The ring size is indicated by an italic / for furanose or p for pyranose, etc. The locants of the linkage are given in parentheses between the symbols a double-headed arrow indicates a linkage between two anomeric positions. In CarbBank, omission of a/p, D/L, or ftp means that this structural detail is not known. 

Note. When the linkage between monosaccharide units is non-glycosidic (as in the phosphate derivative shown below), use of the glycan terminology is inappropriate other methods of polymer nomenclature should be employed [20],... 

Disaccharides are condensation products of two monosaccharide units. Examples are maltose and sucrose. 

Polysaccharides are condensation products of more than ten monosaccharide units examples are the starches and dextrins, which may be linear or branched polymers. Polysaccharides are sometimes classified as hexosans or pentosans, depending upon the identity of the constituent monosaccharides. 

Monosaccharides, the molecular units of the saccharides, are carbohydrate molecules containing between three and six carbon atoms. Oligosaccharides contain small chains of two to ten monosaccharide units, and polysaccharides contain long-chain polymers of monosaccharides. 

Polysaccharides formed from a-glucose are called starches. A starch stores sugar until it is needed for energy production. Three important starches are glycogen, which animals produce in their livers, and amylose and amylopectin, produced by plants through photosynthesis. On average, plant starch is about 20% amylose and 80% amylopectin. Each of these polysaccharides contains glucose as its monomer, but they differ in how the monosaccharide units are linked. 

Carbohydrates are classified based upon the products formed when they are hydrolyzed. Monosaccharides are simple sugars that cannot be broken down into simpler sugars upon hydrolysis. Examples of monosaccharides are glucose, ribose, deoxyribose, and fructose. Disaccharides contain two monosaccharide units and yield two monosaccharides upon hydrolysis. Examples of disaccharides are lactose, maltose, and sucrose. Polysaccharides are polymers of monosaccharide units and yield many individual monosaccharides upon hydrolysis. Examples of polysaccharides are starch, glycogen, and cellulose. 

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