Importance of Polysaccharides

Introduction

Polysaccharides are also called or termed polycarbohydrates. These are the most abundant (easy to be found) carbohydrates found in food materials. Polysaccharides can also be defined as the long chain polymers (carbohydrates) composed (formed) of monosaccharide (simpler) units bounded together by the glycosidic linkages. There are broadly two types of polysaccharides and those are- Homopolysaccharides and Heteropolysaccharides.

Cellulose, starch, and glycogen are examples of Homopolysaccharides, while Hyaluronic acid and Heparin are examples of Heteropolysaccharides. Polysaccharides are not sweet. Many of them are also insoluble in water, they are hydrophobic (away from water) in nature. They are compact materials with an osmotically inactive nature. They are used to store energy in organisms. They also allow for changes in the concentration (c) gradient.

What is a Polysaccharide?

Polysaccharides are polycarbohydrates that are easily found in food materials. Polysaccharides are defined as long-chain polymeric (in form of polymer) carbohydrates composed (formed) of monosaccharide (simpler) units bound together by the glycosidic linkages. This type of carbohydrate can easily react with the water $\mathrm{(H_{2}O)}$ using a catalyst named amylase enzymes, which produces constituent sugars (monosaccharides (simplest) or oligosaccharides). They can vary in structures from linear (l) to highly branched. Some examples include storage polysaccharides like starch, galactogen, and glycogen. And also, some structural polysaccharides such as chitin and cellulose. Polysaccharides are further divided into two categories and those are- homopolysaccharides and heteropolysaccharides. This division is based on the nature of monosaccharide units. Polysaccharides are an important or a very useful class of biological polymers. Polysaccharides finds several uses in industries.

SarahGreenwood, Simple Polysaccharide Hydrolysis, CC BY-SA 4.0

Types of Polysaccharides

As we know polysaccharides are polymers formed of several monomeric units. These monomeric units might be of the same type or distinct types. So, polysaccharides are categorized or classified based on monosaccharide units that are used for their formation-

• Homopolysaccharides − These are also called Homoglycans. When the monosaccharides or monomeric units are of the same or similar type, they are called homopolysaccharides. Ex- starch, glycogen, cellulose, and chitin.

• Heteropolysaccharides − These are also called Heteroglycans. When the monosaccharide or monomeric units are of different or distinct types, they are called homopolysaccharides. Ex- gamma globulins, hyaluronic acid, heparin, e.tc.

Polysaccharides can also be divided into two categories based on their functional roles-

• Storage polysaccharides − These types of polysaccharides are used to store food materials or to reserve energy. Examples- starch (s) and glycogen (gly).

• Structural polysaccharides − These polysaccharides are used for the creation or development of structural components of the cells including cell walls, such as hemicellulose, cellulose, and lignin.

Characteristics of Polysaccharides

Following are some of the features or characteristics of polysaccharides-

• Polysaccharides or glycans are a form or type of non-sugar.

• Polysaccharides are the biological (bio) components (constituents) with a significant (considerable) molecular weight.

• Many polysaccharides are insoluble (not soluble) in water.

• Polysaccharides are non-sweet.

• With the help of the Desiccation process, we can covert polysaccharides into an amorphous powder.

• Polysaccharides are polymers made of simple sugars that are connected by glycosidic linkages, and the connections are covalent.

• In the polysaccharides, the terminal ends might be either reducing (the terminal (last) carbon atom is not involved or contribute to the glycosidic linkage) or non- reducing (the terminal (last) atom involved or contributes to the glycosidic bond).

• Polysaccharides can be represented or denoted by the general formula- $\mathrm{(C_{6}H_{10}O_{5})_{n}}$, where n denotes the number of monosaccharides (monosaccharide units) and can range from 100 to 2500.

Functions of Polysaccharides

Following are some functions of the polysaccharides-

• They are used to store energy in the organisms (living).

• These molecules are hydrophobic because it contains multiple hydrogen (𝐻) bonds that cannot be invaded by the water molecules.

• They allow or permit for changes in the concentration (c) gradient which further influences or affects the uptake of essential nutrients and water by the cells.

• They also provide support to the cells if required. The cell walls of the plants (living organism) is made up of polysaccharide cellulose, which provides (gives) support to the cell wall of the plant. Also, in insects and fungi, chitin (type of polysaccharide) plays an important role by providing support to the extracellular wall (matrix) around the cells.

• Many (several) polysaccharides can also become covalently bonded with the lipids and proteins (p) to give or form glycolipids and also glycoproteins. These formed glycolipids and glycoproteins are used to send signals or messages between or within the cells.

Conclusion

Polysaccharides are also called or are considered polycarbohydrates. These are the most abundant (easy to found) carbohydrates found in food materials. Polysaccharides can also be defined as the long chain polymers (carbohydrates) composed (formed) of monosaccharide (simpler) units bounded (attached) together by the glycosidic linkages. There are broadly two types of polysaccharides and those are- Homopolysaccharides and Heteropolysaccharides.

Cellulose, starch, and glycogen are examples of Homopolysaccharides, while Hyaluronic acid and Heparin are examples of Heteropolysaccharides. Polysaccharides can also be classified into two categories based on their functional roles- Storage polysaccharides and structural polysaccharides. Polysaccharides are not sweet. Many of them are also insoluble in water, they are hydrophobic (away from water) in nature. They are compact materials with an osmotically inactive nature. They are used to store energy in organisms. They also allow for changes in the concentration (c) gradient.

FAQs

1. What are the different types of carbohydrates?

Different forms of carbohydrates are-

• Monosaccharides − These are simple sugars. And these sugars cannot be hydrolyzed into simple sugar. The simplest form of carbohydrates is the three- carbon (3-C) dihydroxyacetone and also triose glyceraldehyde. Further classified forms are- glucose, galactose, fructose, e.tc.

• Oligosaccharides − These are the saccharide polymers containing or consisting of a small number (two to ten) of monosaccharides (simpler sugars). There are several functions of oligosaccharides including cell recognition and also cell adhesion. Examples- Fructooligosaccharides, human milk oligosaccharides, and galactooligosaccharides.

• Polysaccharides − Polysaccharides are long chain polymers containing more than 10 units of monosaccharides linked or connected through glycosidic linkages. Examples- starch, cellulose, e.tc.

2. What is the desiccation process?

Desiccation is defined as the process which converts the materials into a state of extreme dryness, or it is defined as the process of extreme drying.

3. What do you mean by glycosidic bond or linkage?

A glycosidic bond or glycosidic linkage is defined as the type of covalent bond that usually joins a sugar or carbohydrate molecule to another group which may or may not be the carbohydrate (another one).

4. What do you mean by Hemicellulose?

• Hemicellulose is a type of polysaccharide that is made up of a variety of different sugars found in plants.

• This cellulose contains glucose $\mathrm{(C_{6}H_{12}O_{6})}$ and acetyl derivatives of the glucose molecules.

• Similar to cellulose, these are also found in the plant cell wall and also provide the required strength to the cells.

5. Give some examples of structural polysaccharides?

Some examples of structural polysaccharides are- Cellulose and chitin.