Polysaccharides

Introduction

One of the most important types of carbohydrates is polysaccharides in which starch, cellulose, glycogen and some more elements are included. Polysaccharides are key structural components of a plant cell. Different types of monosaccharide are important in developing different polysaccharides. Each polysaccharide possesses an immense significance that is helpful in maintaining the source of energy.

Definition: Polysaccharides

Complex carbohydrates are commonly known as polysaccharides that are formed with a chain of monosaccharide. The chains are attached with a bond and these chains are glycoside. There are two main fundamental types of polysaccharides, namely, heteropolysaccharides and homopolysaccharides.Starch is considered one of the most important and common types of carbohydrate. Starch is present in most food and therefore is divided by different molecular structures. Some specific polysaccharides can possess a straight chain that is known as linear polysaccharides. The other type of polysaccharide is branched polysaccharide.

Structure of Polysaccharides

A proper and almost same fundamental mechanism is found within most of the polysaccharides. The formation procedure of glycoside linkages is associated with the generation of monosaccharide. In an oxygen molecule, two carbon rings are found that form an important glycoside linkage.

This kind of bond is produced at the time when a certain group of hydroxyl is removed from the carbon of a molecule. At that time, the hydrogen is also removed from another hydroxyl group of monosaccharide. This whole process is known as a dehydration reaction. The structural component of molecules states that the quality of all polysaccharides varies because of the differences in the nature of chains.

Types of Polysaccharides

Types of available monomer in a cell’s molecule help in differentiating the polysaccharides into two types.

Figure 2: Polysaccharide types of monomer units and their binding

• Homopolysaccharides: In this type of polysaccharides, same types of monosaccharides are available. The homopolysaccharide polysaccharides included glycogen, inulin, cellulose and starch. A large molecular chain is the key component of glycogen that is found mainly in animals and fungi. Cellulose is the main component of a plant’s cell. Long chains of $\mathrm{\beta}$-glycosides are important components of cellulose.

  Condensation of amylopectin and amylose is the main requirement for forming starch that is found mainly in seeds, fruits and plants. A certain number of important fructofuranose molecules are an important component of inulin. Inulin is found mainly in the tubers of artichoke and dahlia.

• Heteropolysaccharides: In this type of polysaccharide more than one type of monosaccharide is available. The most important heteropolysaccharides include Chondroitin-4-sulphate, hyaluronic acid, gamma globulin and heparin. N-acetyl-glucosamine and D-glucuronic acid are important components that make hyaluronic acid that is found within skin and tissue.

  Another important type of polysaccharide is chondroitin-4-sulphate, which is made of N-acetyl-D-galactosamine-4-O-Sulphate and D-glucuronic acid. In cartilages, this polysaccharide is found. The three most important components are L-iduronic acid, D-glucuronic acid, and N-sulpho-D-glucosamine.

Examples of Polysaccharides

Most renowned and important polysaccharides include cellulose, starch and glycogen. All these three polysaccharides possess immense significance in a living cell. Functions, played by these polysaccharides are responsive and most impactful for a living being. Components of sugars are important as in this D-mannose and D-galactose is included. Polysaccharides are useful in providing proper support to a cell.

Characteristics of Polysaccharides

There are certain characteristics of polysaccharides that play an important role in performing all associated tasks of all polysaccharides.

• The formation of crystals is not affected by desiccation.

• No such sweet flavour is found in polysaccharides.

• Molecules are not infiltrated by water that is impacted by different hydrogen bonds.

• Polysaccharides are composed of oxygen, carbon and hydrogen.

• The ratio of hydrogen and oxygen is 2:1.

• All polysaccharides are carbohydrates that possess a certain molecular weight.

• Within a cell, all polysaccharides are osmotically inactive and compact in nature.

• Most polysaccharides are responsible for extracting white powder.

• All polysaccharides are found to be hydrophobic in nature.

Functions of Polysaccharides

Each type of polysaccharide plays an individual function in a structural organization within both animals and plants.

• Polysaccharides act as efficient storage of energy within all organisms.

• The presence of multiple hydrogen bonds leads water to lose its capability in invading molecules.

• The concentration gradient is changed which is influential in up-taking water and all nutrients within the cell.

• Proteins and lipids bond some polysaccharides covalently. The formation of both glycoproteins and glycolipids is also connected to the function of polysaccharides. Both of these components are useful in transporting signals within cells.

• An extracellular matrix is developed around a cell of fungi and insects. This cell wall is generated to support the body of fungi and insects.

Conclusion

Almost all monosaccharide components are important in developing and differentiating all available polysaccharides. Two types of polysaccharides are there in which multiple types of polysaccharides are found. An important structural base of polysaccharides is known as the storage of energy. Repetition of glucose units is important as with this beta-linkages are integrally connected. All types of carbohydrates are associated with important characteristics of polysaccharides.

(FAQs)

Q1. What is the most important similarity between monosaccharide and polysaccharide?

Ans. Both the monosaccharide and polysaccharide possess longs chain, made of molecules. A monosaccharide is an essential sugar that consists of a molecular chain and polysaccharide are carbohydrates in which different molecules are present.

Q2. Which polysaccharide is indigestible for humans?

Ans. Among all types of polysaccharides, cellulose is the most common one. In humans, the lack of proper enzymes is the reason that is not helpful for digesting cellulose.

Q3. What is the reason behind considering polysaccharides as a stored fuel?

Ans. Almost all polysaccharides are great storage of energy. Plants can depend easily on polysaccharides as these can be used as fuel in providing energy.