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A polysaccharide is a lengthy chain of carbohydrates made up of several sugar molecules linked together by glycosidic bonds. Examples of polysaccharides include: Polysaccharides Carbohydrates include starch, cellulose, and glycogen. Carbohydrates, as we all know, are a key source of food and are required for the survival of living things. Carbohydrates are made up of two fundamental chemicals, aldehydes and ketones, which are made up of Carbon, Hydrogen, and Oxygen atoms. Examples of polysaccharides include: Glycogen, Cellulose, and Starch Polysaccharides have the general formula Cx(H2O)Y, where x is the number of carbon atoms (usually a large number between 200-2500) Polysaccharides are a type of biological polymer that typically have more than 10 monosaccharide units. Oligosaccharides, on the other hand, are polysaccharides with three to ten monosaccharide units. Biological polysaccharides assist live organisms in completing a variety of functions, including structural and energy storage functions. Cellulose and chitin are two examples of structural polysaccharides; cellulose, the most prevalent organic molecule on Earth, is found in the cell walls of plants and other organisms. Polysaccharide Poly means many,’ and saccharide means sugar,’ therefore a polysaccharide is made up of a lot of sugar molecules. Glucose is found in three main polysaccharides: starch, glycogen, and cellulose. In plants and animals, starch and glycogen serve as short-term energy storage. Glycosidic linkages connect the glucose monomers.
Starch
Starch is the most major carbohydrate component in the human diet, accounting for more than half of our total carbohydrate consumption. It is found in the form of granules in plants, and they are particularly plentiful in seeds (particularly cereal grains) and tubers, where they serve as a type of carbohydrate storage.
During periods of low photosynthetic activity, the breakdown of starch to glucose nourishes the plant. Although we often think of potatoes as “starchy” food, other plants have a considerably higher starch content (potatoes 15 %, wheat 55%, corn 65%, and rice 75 %). The starch used in commercial products is a white powder. Amylose and amylopectin are two polymers found in starch. Natural starches contain approximately 10%–30% amylase and 70%–90% amylopectin. Amylose is a linear polysaccharide made up entirely of D-glucose units connected by 1,4-glycosidic bonds.
Experimental data suggest that amylose is coiled like a spring, with six glucose monomers each turn, rather than a straight chain of glucose units. Amylose has just enough capacity in its core when coiled in this way to accommodate one iodine molecule. The development of the amylose-iodine complex gives starch its distinctive blue-violet colour when it is treated with iodine. This colour test may detect even trace levels of starch in a solution.
Amylopectin is a branched-chain polysaccharide made up of glucose units linked largely by 1,4-glycosidic bonds, but with a few 1,6-glycosidic linkages that provide branching. Many thousands of glucose units can be found in one amylopectin molecule, with branch points every 25–30 units. Because the helical shape of amylopectin is broken by chain branching, amylopectin generates a less vivid reddish-brown instead of the deep blue-violet hue amylose produces with iodine. Dextrins are medium-sized glucose polysaccharides. The presence of dextrins generated when clothing is ironed is responsible for the shine and rigidity conferred by starch. Dextrins are employed as adhesives on stamps, envelopes, and labels, as binders to hold pills and tablets together, and as pastes due to their characteristic stickiness when wet. Because dextrins are easier to digest than starch, they are widely used in the commercial manufacture of infant meals.
The full hydrolysis of starch releases glucose in three stages:
starch → dextrins → maltose → glucose
Several enzymes known as amylases in the human body break down starch into usable glucose units in a sequential manner.
Cellulose
The structural component of plant cell walls is cellulose, a fibrous carbohydrate found in all plants. Because the world is covered in vegetation, cellulose is the most prevalent of all carbohydrates, accounting for more than half of all carbon found in plants. Cotton fibers and filter paper are almost entirely made of cellulose (approximately 95%), wood is around 50% cellulose, and the dry weight of leaves is roughly 10%–20% cellulose. The most common application of cellulose is in the production of paper and paper goods. Despite an increase in the usage of non cellulose synthetic fibres, rayon (produced from cellulose) and cotton still account for more than 70% of textile production. cellulose, like amylose, is a glucose linear polymer. It varies from amylose in that the glucose units are linked together by -1,4-glycosidic connections, resulting in a more prolonged structure. Because of the strong linearity, there is a lot of hydrogen bonding between the OH groups on adjacent chains, which causes them to pack tightly into fibres. As a result, cellulose doesn’t react well with water or other solvents. Cotton and wood, for example, are fully water-insoluble but have high mechanical strength. Because cellulose lacks a helical structure, it is unable to bond to iodine and produce a colourful result. Although complete acid hydrolysis of cellulose provides D-glucose, humans are unable to use it as a source of glucose. We can eat potatoes but not grass because our digestive fluids lack enzymes that can hydrolyze the -glycosidic bonds found in cellulose. Certain bacteria, on the other hand, can digest cellulose because they produce the enzyme cellulase, which catalyses cellulose breakdown. Herbivorous animals (such as cows, horses, and sheep) can convert cellulose from plant material into glucose for energy because these microbes are present in their digestive tracts. Termites also have cellulase-secreting bacteria, allowing them to eat wood. This example shows the great stereospecificity of biological processes once again.
Glycogen
The structural component of plant cell walls is cellulose, a fibrous carbohydrate found in all plants. Because the world is covered in vegetation, cellulose is the most prevalent of all carbohydrates, accounting for more than half of all carbon found in plants. Cotton fibres and filter paper are almost entirely made of cellulose (approximately 95%), wood is around 50% cellulose, and the dry weight of leaves is roughly 10%–20% cellulose. The most common application of cellulose is in the production of paper and paper goods. Despite an increase in the usage of non cellulose synthetic fibres, rayon (produced from cellulose) and cotton still account for more than 70% of textile production. cellulose, like amylose, is a glucose linear polymer. It varies from amylose in that the glucose units are linked together by -1,4-glycosidic connections, resulting in a more prolonged structure. Because of the strong linearity, there is a lot of hydrogen bonding between the OH groups on adjacent chains, which causes them to pack tightly into fibres. As a result, cellulose doesn’t react well with water or other solvents. Cotton and wood, for example, are fully water-insoluble but have high mechanical strength. Because cellulose lacks a helical structure, it is unable to bond to iodine and produce a colourful result. Although complete acid hydrolysis of cellulose provides D-glucose, humans are unable to use it as a source of glucose. We can eat potatoes but not grass because our digestive fluids lack enzymes that can hydrolyze the -glycosidic bonds found in cellulose. Certain bacteria, on the other hand, can digest cellulose because they produce the enzyme cellulase, which catalyses cellulose breakdown. Herbivorous animals (such as cows, horses, and sheep) can convert cellulose from plant material into glucose for energy because these microbes are present in their digestive tracts. Termites also have cellulase-secreting bacteria, allowing them to eat wood. This example shows the great stereospecificity of biological processes once again.
Conclusion
A polysaccharide is a lengthy chain of carbohydrates made up of several sugar molecules linked together by glycosidic bonds. Starch is the most major carbohydrate component in the human diet, accounting for more than half of our total carbohydrate consumption. It is found in the form of granules in plants, and they are particularly plentiful in seeds (particularly cereal grains) and tubers, where they serve as a type of carbohydrate storage. It contains two glucose-based polymers: amylose (linear) and amylopectin (branched). Glycogen is a type of energy storage found in mammals. It’s a polymer made up of glucose units that are branched. It has a higher branching structure than amylopectin. In plants, cellulose is a structural polymer of glucose units. It’s a linear polymer with 1,4-glycosidic linkages connecting the glucose units.
