Polysaccharides, Chemistry tutorial

Introduction:

Polysaccharides are basically long polymers of monosaccharides and their derivatives. Dissimilar to proteins or nucleic acids, such polymers can be either linear or branched and they can have only one kind of monosaccharide (that is, Homopolysaccharides), or more than one (that is, Heteropolysaccharides). Polysaccharides can as well be roughly categorized into groups according to their two major functions: energy storage and their contributions to the structural components of cells.

Define:

A polysaccharide is a long-chain carbohydrate manufactured of smaller carbohydrates known as monosaccharides which are typically employed by our bodies for energy or to assist by cellular structure. Each and every monosaccharide is linked altogether through glycosidic bonds to form the polysaccharide. The typical polysaccharide is between 200 and 2500 monosaccharides long, and they can be either linear or branched carbon chains. Generally, the structure of polysaccharides is six-carbon repeating monosaccharides linked altogether through oxygen. The chemical formula is often (C6H10O5)n, where 'n' is the number bigger than 40. The specific formation of the polysaccharide is based on its use.

Polysaccharides are frequently quite heterogeneous, having slight modifications of the repeating unit. Based on the structure, such macromolecules can encompass dissimilar properties from their monosaccharide building blocks. They might be amorphous or even insoluble in the water. If all the monosaccharides in a polysaccharide are of similar kind, the polysaccharide is known as a homopolysaccharide or homoglycan, however if more than one kind of monosaccharide is present they are known as Heteropolysaccharides or heteroglycans.

Use of Polysaccharides:

Polysaccharides encompass various roles. Polysaccharides like starch, glycogen and dextrans are all stored in the liver and muscles to be transformed to energy for later use. Amylose and Amylopectin are the polysaccharides of starch. Amylose consists of a linear chain structure made up of hundreds of glucose molecules which is linked through a alpha 1, 4 glycosidic linkage. Because of the nature of such alpha 1, 4 bonds, the macromolecule often supposes a bent shape. The starch molecules make a hollow helix which is appropriate for simple energy access and storage. This provides starch a less fibrous quality and a more granule-like shape that is better matched for storage. Dissimilar to the linear structure of Amylose, the Amylopectin starches are branched having an alpha 1, 6 glycosidic linkages around each and every 30 glucose units. Similar to amylose it is a homopolymer comprised of numerous glucose units. Glycogen is found in animals, and it is branched similar to amylopectin. This is made by mainly alpha 1, 4 glycosidic linkages however branching takes place more often than in the amylopectin as alpha 1,6 glycosidic linkages take place around each and every ten units. The other polysaccharides encompass structural functions. For illustration, cellulose is a main component in the structure of plants. Cellulose is prepared of repeating beta 1, 4-glycosidic bonds. Such beta 1,4-glycosidic bonds, dissimilar the alpha 1,4 glycosidic bonds, force cellulose to form long and sturdy straight chains which can interact by one other via hydrogen bonds to make fibers.

What are the various kinds of Polysaccharides?

Whenever the polysaccharide is made up of similar kind of monosaccharides, they are termed as homopolysaccharide or homoglycan, if it is made up of various kinds of monosaccharides; they are termed as hetero-polysaccharides or heteroglycans. The three general polysaccharides are Starch, Glycogen and Cellulose.

Starches: As Starches are fundamentally glucose polymers they require the enzyme Amylase to be broken down into glucose or to be digested. Plants store glucose in the form of starches.

Starches are the glucose polymers in which glucopyranose units are bonded via alpha-linkages. This is made up of a mixture of amylose (15-20 %) and amylopectin (80-85 %). Both amylose and amylopectin are the polymers of glucose connected mostly by α(1→4) bonds. Amylose comprise of a linear chain of some hundred glucose molecules and amylopectin is a highly branched molecule made up of some thousand glucose units having branching occurring by α(1→6) bonds each and every 24 to 30 glucose units. The percentage of amylose and amylopectin differs based on the source; for illustration, the percentage of amylopectin is higher in medium-grain rice and waxy potatoes, however lower in long-grain rice and russet potatoes.

The formation of starches is the manner which plants store glucose. Starches are insoluble in water. They can be digested via hydrolysis, catalyzed by enzymes termed as amylases, which can break the alpha-linkages (that is, glycosidic bonds). Humans and other animals encompass amylases, therefore they can digest starches. Potato, wheat, rice and maize are main sources of starch in the human diet.

Glycogen: This is a storage made up of glucose that is broken down to glucose when required via animals and humans.

Glycogen is the main storage form of glucose in animal cells. Glycogen is a highly branched polymer of around 30,000 glucose residues and a molecular weight between 106 and 107 daltons. Most of the glucose residues are connected by α-1,4 glycosidic bonds. Around one in 10 glucose residues as well makes an α-1,6 glycosidic bond by an adjacent glucose that yields in the creation of a branch. Glycogen consists of only one reducing end and a large number of non-reducing ends having a free hydroxyl group at carbon-4. The branches raise the solubility of glycogen.

Cellulose: These are the polysaccharides which are the components of plants and are employed as building material. They provide both shape and structure to the plants. Cellulose can't be digested via humans and that is the reason we can't digest grass as it is made up of cellulose. Horses, cows, sheep, goats can digest cellulose as they encompass symbiotic bacteria in their intestinal tract and it is these bacteria by their enzymes which assist in digesting the cellulose. Humans still make use of Cellulose in the form of cotton, paper to make a lot of products that we are all too well-known with.

What are the various types of Structural Polysaccharides?

Chitin:

This is modified polysaccharides which contain Nitrogen. This is derived from glucose. It makes the external skeleton in numerous animals and is as well bio-degradable. These polysaccharides look like cellulose in structure and the protein keratin in terms of function. This polysaccharide has a broad use in the agricultural, industrial and medical fields. Chitin consists of proven great utilization as a fertilizer and as well to raise the immunity among the plants. This is employed as a binder in dyes, adhesives and fabrics in the industrial area. It is as well employed as a surgical thread in the field of medicine due to its capability to dissolve.

Pectin:

This is the polysaccharide which forms the primary cell walls of numerous terrestrial plants. This is an illustration of Heteropolysaccharides. It consists of different utilizations in the food industry as it acts as a gelling agent for jellies and jams. It is as well employed as a food thickening agent and stabilizer in milk and juices.

Arabinoxylans: This is a polysaccharide found in the primary and secondary cell wall of plants that is, wood and as well in the cereal grains. This is a combination of arabinose and xylose.

Bacterial polysaccharides:

Bacterial polysaccharides stand for a diverse range of macromolecules which comprise peptidoglycan, lipopolysaccharides, capsules and exopolysaccharides; compounds whose functions range from the structural cell-wall components (like peptidoglycan) and significant virulence factors (example: Poly-N-acetylglucosamine in S. aureus), to permitting the bacterium to survive in harsh environments (for illustration, Pseudomonas aeruginosa in the human lung). Polysaccharide biosynthesis is a tightly controlled, energy intensive procedure and understanding the slight interplay between the regulation and energy conservation, polymer alteration and synthesis and the external environmental functions is a giant area of research. The potential advantages are enormous and must enable, for illustration, the growth of novel anti-bacterial strategies (like new antibiotics and [vaccine]s) and the commercial exploitation to build up novel applications.

How are Polysaccharides processed in our Body?

The food we eat is mixed by enzymes discharged via the body at different points to assist in the digestion of the various kinds of molecules like fats, proteins and carbohydrates. As chewing helps in breaking down the carbohydrates to smaller chunks, it is in the stomach followed via the small intestine which the final breakdown of the polysaccharides occurs. The acid discharged in the stomach breaks them down to monosaccharides. The monosaccharides are glucose molecules that are the fundamental energy giving molecules. The glucose is further broken down in the cells to molecules of ATP - Adenosine Triphosphate. This is only if glucose is broken down to ATP can carbohydrates providing energy which can use by the body to do work. Whereas the surplus ATP molecules are transformed by the liver to glycogen, these can be later broken down to glucose whenever required by the body.

What is Dietary Fiber?

Dietary Fiber is a kind of polysaccharide which our body can't digest. As women require at least 25 grams of fiber per day, men require anywhere from 30 to 38 grams per day. Dietary fiber is fiber which our body can't digest to get any nutrients out of it and is the indigestible part that absorbs water as it moves down the alimentary canal and assists in bowel movement. However, then not all the fibers are dietary fibers. Some of the examples of fibers are non-starch polysaccharides - cellulose, lignin, chitins and pectin, mucilage and gum. Both the fibers and Dietary fibers are present in the soluble and insoluble forms. Dietary fiber is merely present in plant food that comprises fruits, nuts and vegetables. Good sources of dietary fiber are bran cereals, broccoli, beans, whole-wheat breads, peas, grains and cereals. The soluble dietary fiber assists us in preventing the constipation, decreasing cholesterol levels, treatment of hemorrhoids and diverticulosis. The soluble fibers can only be digested by the assistance of the bacteria present in our digestive tract. The insoluble fiber is indigestible and assists in bowel movement.

What is Ganoderma Polysaccharide?

Polysaccharides are present in an extremely high concentration in 2 Asian herbs, Ganoderma Lucidum and Cordyceps Sinensis. As the Ganoderma herb consists of Ganoderma Polysaccharides, the Cordyceps herb includes Cordyceps Polysaccharides. Both such herbs are proven to enhance immune system that assists us in helping with diabetes and cancer.

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