Carbohydrates Term Paper Example | Topics and Well Written Essays - 1500 words

Carbohydrates - Term Paper Example Structural composition of carbohydrates Structurally, carbohydrates exist as polyhydroxy or alcohol groups containing ketone or aldehyde functional groups (Engel, Gary and Reid, 115). These functional groups are responsible for the distinct chemical and physical properties of the different types of carbohydrates. Normally, carbohydrates are made of monosaccharides, which are the basic and the simplest units. Therefore, carbohydrates are polymers, consisting of monosaccharide monomers. The chemical and physical properties of carbohydrates depend on the type of monosaccharide monomers, the length of the polymer chain and the method used to join the basic units (Linhard and Bazin 55). Carbohydrates are divided into different categories depending on the length of the carbon chain. These categories include monosaccharide, disaccharides, oligosaccharides and polysaccharides. Monosaccharides are single and the simplest carbohydrate molecules, comprising of five or six carbon chains (Linhard and Bazin 57). Examples of monosaccharide include five carbon (pentose) sugars such as xylose, arabinose and ribose. Hexoses, which are six carbon sugars, are the most common simple sugars. They include fructose, mannose, glucose and fructose. Green plants through photosynthesis process naturally synthesize glucose. During photosynthesis, carbon dioxide and water combine in presence of light energy to form glucose (Voet, et al, 164) 6CO2 + 6H2O + energy> C6H12O6 + 3O2 The monosaccharides synthesized from the green plants undergo polymerization reactions to form disaccharides and other complex carbohydrates. Other methods natural processes that produce glucose include chemosynthesis in autotrophic bacteria and biosynthesis (McKee and McKee, 306). The presence of many chiral centers on the structure of glucose results into formation of two structural conformations, which could be either enantiomer or diastereomer. Enantiomers are mirror images. Glucose exhibits two enantiomeric struc tures namely, D and L glucose. Both of these structures demonstrate different physical and chemical properties (Pigman, 79) Disaccharides consist of two monosaccharide molecules that undergo polymerization reaction forming the longer chain carbohydrate (Timberlake, 127). Polymerization reaction is building up process, where small units (monomers) link together to form a complex molecule (polymer). Glycosidic bonds link the two-monosaccharide molecules after undergoing polymerization reaction. Polymerization process leads to formation of disaccharides, oligosaccharides and polysaccharides. These reactions occur between hydroxyl group of two different molecules leading to formation of covalent glycosidic bonds (Engel, Gary and Reid, 217-228). Examples of disaccharide include sucrose, maltose and lactose. Sucrose is formed when fructose and glucose undergo polymerization reactions. Therefore, fructose and glucose are sucrose monomers. Similarly, maltose is formed from the reaction of t wo glucose molecules while lactose from glucose and galactose molecules. Hence, glucose molecules are maltose monomers. Oligosaccharides comprises of about three to ten monosaccharides that are linked together after undergoing polymerization reactions. Examples include fructo- oligosaccharide and galacto-oligosaccharide (Pigman, 162). Polysaccharides comprise of long carbon chains formed by numerous monosaccharide units. The large number of number of monosaccharide monomers in polysaccharides result to