Carbohydrates Monosaccharides Polysaccharides

Biopolymers are the naturally occurring macromolecular materials that are the components of all living systems. There are three principal categories of biopolymers, each of which is the topic of a separate article in the Eniyclopedia proteins (qv) nucleic acids (qv) and polysaccharides (see Carbohydrates Microbial polysaccharides). Biopolymers are formed through condensation of monomeric units ie, the corresponding monomers are amino acids (qv), nucleotides, and monosaccharides, for proteins, nucleic acids, and polysaccharides, respectively. The term biopolymers is also used to describe synthetic polymers prepared from the same or similar monomer units as are the natural molecules. 

Carbohydrates are classified as either simple or complex. Simple sugars, or monosaccharides, are carbohydrates such as glucose and fructose that can t be broken down into smaller molecules by hydrolysis with aqueous acid. Complex carbohydrates, or polysaccharides, are compounds such as cellulose and starch that are made of many simple sugars linked together. On hydrolysis, polysaccharides are cleaved to yield many molecules of simple sugars. 

Know the meaning of carbohydrate, monosaccharide, oligosaccharide, polysaccharide, disaccharide, trisaccharide. 

Wine is one of the most complex and interesting matrices for a number of reasons. It is composed of volatile compounds, some of them responsible for the odor, and nonvolatile compounds which cause taste sensations, such as sweetness (sugars), sourness (organic acids), bitterness (polyphenols), and saltiness (mineral substances Rapp and Mandary, 1986). With a few exceptions, those compounds need to be present in levels of 1%, or even more, to influence taste. Generally, the volatile components can be perceived in much lower concentrations, since our organs are extremely sensitive to certain aroma substances (Rapp et ah, 1986). Carbohydrates (monosaccharides, disaccharides, and polysaccharides), peptides, proteins, vitamins, and mineral substances are among the other wine constituents. 

The carbohydrate class, polysaccharide, represents compounds in which the molecules contain many units of monosaccharides joined together by glycoside links. Upon complete hydrolysis, a polysaccharide delds monosaccharides. Starch is the most valuable polysaccharide. The starch molecules (amylose and anylopectin) are tree-like, containing 250 to 1000 or more glucose units per molecule joined together through alpha linkages. 

Polysaccharides You may have seen large carbohydrate polymers referred to as complex carbohydrates in nutritional references. Another name for a complex carbohydrate is polysaccharide, which is a polymer of simple sugars that contains 12 or more monomer units. The same type of bond that joins two monosaccharides in a disaccharide links them together in a polysaccharide. Pasta is a good source of polysaccharides. The pasta shown in Figure 24-10b contains large amounts of starch, a polysaccharide from plants. 

Adsorption can be used to differentiate between free dissolved monomeric phenols and monomeric carbohydrates. Muenster (1982) showed that the sum of both monomeric substance classes in Lake Plussee water comprised between 3 and 10% of the total DOC concentration depending on the resin used. Perdue and co-workers (Lytle and Perdue, 1981 Sweet and Perdue, 1982) utilized Amerlite XAD-7 resin to adsorb humic substances and determined free dissolved amino acids and humic-acid-associated amino acids, as well as monosaccharides, polysaccharides, and humic-bound saccharides in the Williamson river system (Oregon). As a mean, less than 4% of the dissolved amino acids occurred in free dissolved form, and only 2.6% of the total carbohydrates were monosaccharides. This observation as well as some ecophysiological implications are described more extensively in a later section. 

P. Zugenmaier and A. Sarko, Acta Crystallogr., Sect. B, 28, 3158 (1972). Packing Analysis of Carbohydrates and Polysaccharides. 1. Monosaccharides. 

Saccharides see carbohydrates, monosaccharides, disaccharides, oligosaccharides, and polysaccharides. 

Carbohydrates can have a measurable influence on the release and perception of flavors. Carbohydrates change the volatility of compounds relative to water, but the effect depends on the interaction between the particular volatile molecule and the particular carbohydrate. As a general rule, carbohydrates, especially polysaccharides, decrease the volatility of compounds relative to water by a small to moderate amount, as a result of molecular interactions. However, some carbohydrates, especially the monosaccharides and disaccharides, exhibit a salting-out effect, causing an increase in volatility relative to water (Godshall, 1997). 

Match the terms carbohydrate, monosaccharide, disaccharide, and polysaccharide to each of the following (more than one term may fit) ... 

Name two examples from each of the following classes of carbohydrates monosaccharides, disaccharides, and polysaccharides. 

In polysaccharides, consisting of n monosaccharides, the number n is as a rule >10. Hence, the properties of these high molecular weight polymers differ greatly from other carbohydrates. Thus, polysaccharides are often considerably less soluble in water than mono- and oligosaccharides. They do not have a sweet taste and are essentially inert. Well known representatives are starch, cellulose and pectin. 

Total daily carbohydrate intake in the UK is about 277 g in which 110 g is monosaccharides or disaccharides such as sucrose, fructose, glucose, etc. These are relatively easy to isolate analytically. The rest of food carbohydrate is polysaccharide (about 167 g) of which starch (148 g) is the major component. The non-starch polysaccharides (18 5 g) are the major part of what is commonly called dietary fibre. 

Carbohydrates may be divided into monosaccharides, disaccharides and polysaccharides. The monosaccharides under certain conditions react as polyhydroxy-aldehydes or polyhydroxy-ketones two important representatives are glucose CjHjjO (an aldose) and fructose (laevulose) CgHuO, (a ketose). Upon hydrolysis di- and polysaccharides 3deld ultimately monosaccharides. Common disaccharides are sucrose, lactose and maltose (all of molecular formula C,2H2. 0,), whilst starch, dextrin and cellulose, (CjHjoOj), in which n > 4, are typical polysaccharides. 

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. 

Polysaccharide (Sections 25.1 and 25.15) A carbohydrate that yields many monosaccharide units on hydrolysis. 

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. 

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