What is a Polysaccharide?
Polysaccharide is a long chain of carbohydrates whose molecules consist of numerous sugar molecules bonded together by glycosidic linkages. Polysaccharide examples: Starch, Cellulose or Glycogen are polysaccharides Carbohydrates. As we know carbohydrates are a major source of food and necessary for getting energy for the survival of living organisms. Consisting of Carbon, Hydrogen and Oxygen atoms, carbohydrates are made up of two basic compounds, namely aldehydes and ketones.
Polysaccharides are one of the three carbohydrates found in all-natural and processed foods and the other two carbohydrates are monosaccharides and disaccharides.
Monosaccharide Examples: Glucose and Galactose
Disaccharide Examples: Sucrose and Maltose
Polysaccharide Examples: Starch, Glycogen and Cellulose
General Formula of Polysaccharides is Cx(H2O)y where x is the number of carbon atoms (usually a large number between 200-2500)
Polysaccharides are an important class of biological polymers and generally contain more than 10 monosaccharide units, however, oligosaccharides are polysaccharides with three to 10 monosaccharide units. Biological polysaccharides help in performing various functions in living organisms, either structural functions or energy storage functions. Two examples of structural polysaccharides include cellulose and chitin; the cell walls of plants and other organisms are composed of cellulose which is considered the most abundant organic molecule on Earth.
Polysaccharide Meaning: Poly means ‘many’ and saccharide means ‘sugar’; so a polysaccharide contains many sugar molecules.
See the below polysaccharide structure for a clearer understanding.
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Types of Polysaccharides
Heteropolysaccharides and Homopolysaccharides are the two types of polysaccharides that are described in the following:
When more than one kind of monosaccharide is present in the polysaccharide structure, it is known as heteropolysaccharide or heteroglycan. In contrast, homopolysaccharide or homoglycan is the kind of polysaccharide that has the same type of monosaccharides.
Examples of homopolysaccharides are glycogen, cellulose, starch and insulin. Glycogen is made up of a large chain of molecules and is found in animals and fungi. Cellulose is present in the cell wall of the plants and comprises long chains of beta glycosides. Starch is produced by the condensation of amylopectin and amylose; available largely in plants, fruits, seeds, etc. Insulin is composed of numerous fructofuranose molecules linked together in chains, it is found in tubers of artichoke, dahlia, etc.
Examples of heteropolysaccharides are hyaluronic acid, heparin, chondroitin-4-sulfate and gamma globulin. Hyaluronic acid is made up of N-acetyl-glucosamine and is found in connective tissues and skin. Heparin is made up of D-glucuronic acid, N-sulfo-D-glucosamine and L-iduronic acid and it is largely distributed in blood and mast cells. Chondroitin-4-sulfate sugars are D-glucuronic acid and N-acetyl-D-galactosamine-4-O-sulfate. It is found in the cartilages. Gamma globulin is composed of N-acetyl-hexosamine, D-galactose and D-mannose as the component sugars of the polysaccharide and is present in the blood.
Characteristics of Polysaccharides
Many of the polysaccharides are insoluble in water.
These are not sweet.
These are hydrophobic.
These do not form crystals on desiccation.
Polysaccharides can be extracted in the form of a white powder.
These have a high molecular weight as carbohydrates.
These are compact and osmotically active inside the cells.
The hydrogen to oxygen ratio in them is 2:1 and they consist of hydrogen, carbon and oxygen.
Functions of Polysaccharides
Structural Functions- Common sources of energy are nutrition polysaccharides and most of the organisms can easily break down starch into glucose. However, some complex polysaccharides are not very digestible that are known as dietary fibre and these provide important elements in the diet for humans. There are soluble fibre and insoluble fibre that are associated with various functions in the body. The former is responsible for lowering cholesterol levels (bad) in the blood, normalizing blood lipid levels and reducing sugar response after eating. The latter or insoluble fibre reduces the risk of diabetes.
Storage Functions- Storage polysaccharides are starch, glycogen and insulin. A glucose polymer that is insoluble in water is Starch. Both humans and animals have amylases to digest starches easily. Starch can be found in potatoes, rice, wheat and maize. Glycogen is the long-term store for energy and works the best in animal and fungal cells. The primary energy storage takes place in the adipose tissue and glycogen is made by the liver and muscles and also within the brain and stomach by glycogenesis. Glycogen serves as an energy reserve for animals and is the main form of carbohydrate stored in the animal body. It is insoluble in water and yields glucose on hydrolysis.
About Polysaccharides Provided by Vedantu
This article of Vedantu deals with polysaccharides, the other two carbohydrates called monosaccharides and disaccharides have a separate article that includes important study material and therefore these concepts can be studied in-depth with the help of those notes provided by Vedantu.
Three main types of carbohydrates are found in various natural and processed foods, they are as follows-
Monosaccharides - The example of monosaccharides are glucose and Galactose.
Disaccharides – The example of disaccharides are sucrose and maltose.
Polysaccharides – The examples of polysaccharides are starch, glycogen and Cellulose.
Polysaccharides are discussed as a very brief topic in the NCERT book of class 11, in chapter 9 called biomolecules.
Therefore Vedantu provides effective study notes on the topic of polysaccharides, as some students may find it difficult to grasp this concept that is discussed in the NCERT book. After studying the study notes provided by Vedantu students can get a comprehensive understanding of polysaccharides.
The study notes provided by Vedantu on polysaccharides are an extremely important resource for students as they act as a reference guide. The objective of producing this study material is to help students get a comprehensive understanding of the topic that is being discussed and to help them get a good grade in the examination. The study material provided by Vedantu is prepared by expert teachers who have years of experience in this field and are therefore well-versed in the concerned discipline. Class 11 and 12 study material on physics biology and chemistry is also useful for NEET aspirants as the basic foundation of NEET examination is the syllabus of class 11 and 12 physics biology and chemistry.
Students who are wanting to get a glance at the key concepts that are discussed in polysaccharides can go through the notes provided by Vedantu, the link is easily accessible and it can be downloaded in a PDF format for free.
Key Concepts Taught in Chapter 9 Biomolecules Related to the Study of Polysaccharides-
9.1 How to Analyse Chemical Composition?
9.2 Primary and Secondary Metabolites
9.3 Biomacromolecules
9.4 Proteins
9.5 Polysaccharides
9.6 Nucleic Acids
9.7 Structure of Proteins
9.10 Metabolic Basis for Living
9.11 The Living State
9.12 Enzymes
FAQs on Polysaccharides
1. What are polysaccharides?
Polysaccharide is a type of carbohydrate. Carbohydrates are an extremely important source of food and they provide energy that is needed for the survival of many living organisms. A carbohydrate comes under the category of a biomolecule which consists of carbon, hydrogen and oxygen atoms.
Polysaccharides are made up of several long chains of carbohydrate molecules which are composed of many small monosaccharides which is another type of carbohydrate. Polysaccharides are a class of biomolecules. These are extremely complex macromolecules that have an important function in acting as a source of energy in animal cells and they also are present as a structural component of a plant cell. Polysaccharides are divided into homopolysaccharides and heteropolysaccharides, they depend on the type of the monosaccharides.
2. What are the types of carbohydrates?
Mainly three types of carbohydrates are found in all-natural and processed foods. They are – monosaccharides, disaccharides, polysaccharides. Carbohydrates are referred to as biomolecules which consist of carbon, oxygen and hydrogen atoms. The two main components that consist of carbohydrates are aldehydes and ketones
3. What are the characteristics of polysaccharides?
Here are some characteristic features of polysaccharides-
Polysaccharides are not sweet
polysaccharides are insoluble in water
Polysaccharides are hydrophobic
Polysaccharides do not form crystals when desiccation is performed
Polysaccharides can be extracted to form a white powder
Polysaccharides have a high molecular weight
4. Where can I find the study material related to polysaccharides?
The study material on polysaccharides is provided on Vedantu’s website. The links can be easily accessible. The study material is available in PDF format and can be downloaded for free. The concept of polysaccharides can get a little confusing as various terminologies are studied in biology, and this article mainly consists of the many terms that come under the category of carbohydrates and biomolecules. Polysaccharide is a concept that is very briefly discussed in the NCERT book that is prescribed by the Central Board of secondary education, however, this is where Vedantu study notes come to the rescue as they contain separate articles for every particular term that is been discussed with biology and various other subjects. The aim is to provide quality material to students who can get a good grasp of the concepts as they are written in an extremely simplified language.
5. What are the types of polysaccharides?
Polysaccharides can be divided into two categories, they are as follows-
Homopolysaccharides - polysaccharides that consist of the same type of monosaccharides are called homopolysaccharides, some of the examples of homopolysaccharides are – glycogen, Celulose, starch and inulin.
Heteropolysaccharides - polysaccharides that consist of different types of monosaccharides are called hydro polysaccharides, some of the examples of heteropolysaccharides are hyaluronic acid, heparin, chondroitin 4 sulfate, gamma globulin.
6. Describe the Classification of Polysaccharides.
Polysaccharides can be classified into two classes, namely, homopolysaccharides and heteropolysaccharides. The former type is made up of monosaccharide units and examples include cellulose, glycogen and starch. The latter type is made up of two or more types of monosaccharide units. Eg: Agar
7. What are the Examples of Structural Polysaccharides?
Some examples of structural polysaccharides are arabinoxylans, chitin, pectins and cellulose. Arabinoxylans are present in both the primary as well as secondary cell walls of plants and consist of two sugar arabinose and xylose. Cellulose is the structural component of plants; it is found largely in wood, paper and cotton. It is made up of repeated glucose units bonded by beta linkages. Chitin is a naturally occurring polymer and forms the structural component of many animals like exoskeletons. Pectins are complex polysaccharides and are present in most of the primary cell walls and non-woody parts of the plants.
8. Which are the Three Main Polysaccharides Associated with Human Nutrition?
Starch, Cellulose and Glycogen are the three main polysaccharides associated with human nutrition and the first two are obtained from plants; whereas glycogen is the storage polysaccharide made by the human liver and muscles.
