Polysaccharide Definition

noun plural: polysaccharides pol·y·sac·cha·ride, ˌpɒlɪˈsækəɹaɪd any kind of from the team of polymeric carbohydrates developed by lengthy chains of repeating units linked together by glycosidic bonds


The hatchet polysaccharide etymologically way multi saccharides. A saccharide describes the unit structure of carbohydrates. Thus, a polysaccharide is a carbohydrate comprised of countless saccharides, i.e. An ext than ten (mono)saccharide units.

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Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen, usually in the ratio of 1:2:1. Lock are one of the significant classes the biomolecules. They are vital source of energy. They additionally serve as structural components. Together a nutrient, they can be classified into two significant groups: simple carbohydrates and complex carbohydrates. Straightforward carbohydrates, sometimes referred come as just sugar, room those that are readily digested and also serve together a rapid source of energy. Complicated carbohydrates (such together cellulose, starch, chitin, and glycogen) room those that need more time to it is in digested and also metabolized. They regularly are high in fiber and also unlike simple carbohydrates lock are less likely to cause spikes in blood sugar levels.

Characteristics of Polysaccharides

Polysaccharides are identified by the following chemical properties: (1) not sweet in taste, (2) numerous of which are insoluble in water, (3) execute not kind crystals when desiccated, (4) compact and also not osmotically active inside the cells, (5) deserve to be extract to kind white powder, and also (6) basic chemical formula that Cx(H2O)y.

Polysaccharides consists hydrogen, carbon, and also oxygen, just as the other creates of carbohydrates. The ratio of hydrogen atoms to oxygen atom is often 2:1, i beg your pardon is why lock are also described as hydrates that carbon. The basic chemical formula that polysaccharides is (C6H10O5)n. Because of the existence of carbon and also C-C and also C-H covalent bonds, lock are considered as essential compounds similar to various other carbohydrates.

Polysaccharides differ from oligosaccharides and disaccharides based upon how plenty of monosaccharide units space present. Disaccharides are made up of only two monosaccharides. Oligosaccharides have much more than 2 monosaccharides. The ax oligosaccharide is frequently used come describe relatively shorter chains than polysaccharides. Polysaccharides space a kind of biological macromolecule made up of many monosaccharide units.

There are diverse forms of polysaccharides. Their structure ranges from a an easy linear to the much more complex, very branched forms. Numerous of them are heterogenous. Depending upon their composition, they might be amorphous or water-insoluble.

Dehydration Synthesis

The chemical process of joining monosaccharide systems is referred to as dehydration synthesis since it outcomes in the relax of water together a byproduct. One method of manufacturing a polysaccharide is v a condensation reaction together it entails the involvement of sub-units to kind a rather condensed compound through the concomitant relax or loss of water.


Hydrolysis is the procedure of convert polysaccharide into an easy monosaccharide components. While condensation reaction requires the remove of water, hydrolysis uses water molecule. The procedure of converting polysaccharides right into monosaccharides, in particular, is referred to as saccharification. In humans, carbohydrates (apart from monosaccharides) space digested through a collection of enzymatic reactions. These enzymes room salivary amylase, pancreatic amylase, and maltase. Salivary amylase acts on the starch and also breaks it down to maltose. The following site of carbohydrate digestion will be the tiny intestine. The stomach is not connected in the digestion of carbohydrate because the gastric juice inhibits the activity of the outstanding amylase. Thus, the following phase the carbohydrate digestion will be the little intestine. Once the partially-digested carbohydrates with the little intestine, the kidneys secretes pancreatic juices that encompass the pancreatic amylase. This enzyme acts on the partially-digested carbohydrate by breaking them under into basic sugars. The brush border that the little intestine releases digestive enzymes such as isomaltase, maltase, sucrase, and also lactase. Isomaltase digests polysaccharides in ~ the alpha 1-6 linkages, and convert alpha-limit dextrin to maltose. Maltase breaks under maltose (a disaccharide) into two glucose units. Sucrase and lactase digest sucrose and lactose, respectively, into monosaccharide constituents. The epithelial cells at the brush border of the small intestine absorb monosaccharides. Glucose and also galactose are taken inside the intestinal cell (enterocyte) via active transport utilizing glucose transporters (GluT). Fructose is also taken up making use of GluT but the mode of transport is not yet clear (whether that is by active or passive transport). The enterocytes release the monosaccharides into the capillaries via passive transfer (particularly, by promoted diffusion). The basic sugars space then transported to the cell of various other tissues, especially to liver, indigenous the bloodstream. Glucose in the blood may be utilized by the human body to produce ATP. Otherwise, it is transported to the liver, along with the galactose and also fructose (which are mainly converted into glucose), because that storage as glycogen. The continuing to be carbohydrates not soaked up by the little intestine get in the large intestine. The gut flora in the colon metabolizes lock anaerobically (e.g. Fermentation). Together such, this leader to the manufacturing of gases (e.g. Hydrogen, CO2, and also methane) and also fatty acids, such together acetate and butyrate the are immediately metabolized through the body. The gases, in turn, room excreted via breathing them out, eructation (burping), or flatulence.


Glycogenesis is the metabolic procedure of developing glycogen native glucose because that storage. The process occurs mainly in liver and muscle cell in response to high glucose level in the bloodstream. Short polymers of glucose, specifically exogenous glucose, room converted right into long polymers to it is in stored within the cells. Once the body calls for metabolic energy, glycogen is broken down right into glucose subunits v the process of glycogenolysis. Thus, glycogenesis is the opposite process of glycogenolysis.


Glycogenolysis is the procedure of breaking down stored glycogen in the liver so that glucose might be produced for use in energy metabolism. Save on computer glycogen in the liver cells is damaged down into glucose precursors. A single glucose molecule is reduced off native the glycogen and is converted right into glucose 1-phosphate, i beg your pardon in turn, is transformed right into glucose 6-phosphate that can get in glycolysis.


Similar to oligosaccharides, some polysaccharides may serve together glycans in specific glycoconjugates. However, oligosaccharides are an ext often the carbohydrate component 보다 polysaccharides. Glycosylation is the procedure whereby a glycan is enzymatically join to a protein, a lipid, or various other organic molecule. The step-by-step processes of glycosylation vary, depending on the form of glycosylation. For instance, N-linked glycosylation is once the glycan is attached to a nitrogen atom of asparagine or arginine residue of a protein. Conversely,O-linked glycosylation is a procedure where O-linked glycans are attached to the hydroxyl oxygen of serine, threonine, tyrosine, hydroxylysine, or hydroxyproline side chains of a protein. It may likewise be the procedure where the O-linked glycans attach to the oxygen on lipids. Other develops of glycosylation exists, such together C-linked (i.e. Glycan attached come carbon), P-linked (i.e. Glycan, come phosphorus), and S-linked (glycan, come sulfur).

Classification of Polysaccharides

Polysaccharides may be a homopolysaccharide or a heteropolysaccharide depending upon their monosaccharide components. A homopolysaccharide (also called homoglycan) is made up of just one form of monosaccharide vice versa, a heteropolysaccharide (also referred to as heteroglycan) is created of different types of monosaccharides. Based on their function, polysaccharides might be classified as storage or structural polysaccharides. Warehouse polysaccharides room those the are offered for storage. For instance, plants save glucose in the kind of starch. Pets store basic sugars in the type of glycogen. Structure polysaccharides space carbohydrates that have a structural role. Plants have celluloses, which room polymers of repeated glucose devices that space joined through beta-linkages. Particular animals produce chitin that serves together a structure component, because that example, the exoskeleton.

Examples of Polysaccharides

Common instances of polysaccharides room cellulose, starch, glycogen, and also chitin. Cellulose is a polysaccharide consists of a straight chain the β (1→4) attached D-glucose units: (C6H10O5) n. Starch is a polysaccharide carbohydrate (C6H10O5)n consist of of a large number the glucose monosaccharide systems joined with each other by glycosidic bonds uncovered especially in seeds, bulbs, and tubers. Glycogen is a branched polymer of glucose that is mainly produced in liver and also muscle cells, and also functions as secondary long-term energy storage in animal cells. Chitin is a polymer the nitrogen-containing polysaccharide (C8H13O5N)n calculation a tough, protective extending or structural assistance in particular organisms. It renders up the cell walls of fungi and exoskeleton that insects. Other examples of disaccharides space callose, chrysolaminarin, xylan, mannan, fucoidan, galactomannan, arabinoxylan.

Biological Importance

Polysaccharides, just as the various other carbohydrates, are a major source of energy, and therefore are among the key dietary components. Pets consume lock to achieve monosaccharides the they have the right to use to synthesize ATP. ATPs room chemical energy biologically synthesized through aerobic and anaerobic respirations. Glucose is the most common kind of monosaccharide the the cell supplies to synthesize ATP via substrate-level phosphorylation (glycolysis) and/or oxidative phosphorylation (involving redox reactions and chemiosmosis). And one that the sources of glucose is a carbohydrate-containing diet. Too lot carbohydrate in the diet though might lead to wellness problems. Repetitively high blood street level could eventually bring about diabetes mellitus. The gut would also need to exert greater initiative to digest them. Too lot fructose, for instance, can lead come malabsorption in the tiny intestine. As soon as this happens, unabsorbed fructose transported come the huge intestine might be used in fermentation by the colonic flora. This might lead to gastrointestinal pain, diarrhea, flatulence, or bloating. Plants keep excess glucose in the kind of starch. Thus, there room plants that room harvested to use the starch for food preparation and also industrial purposes. Pets store carbohydrate in the kind of glycogen so that once the body needs for an ext glucose, glucose deserve to be taken from this reserve through the process, glycogenolysis. Polysaccharides are likewise essential in life organisms as they serve as structural component of organic structures, such as cellulose and also chitin. Plant cellulose is harvested because that its multifarious uses in the industry.



More info relating come carbohydrates and their function in our diet can be found in the biologic tutorial A balanced Diet – Carbohydrates and also Fat.


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