A monosaccharide is the simplest form of sugars, containing single polyhydroxy aldehyde or ketone unit. Oligosaccharide consists of two or more units of monosaccharides, joined by glycosidic bonds.While the Polysaccharide consists of more than 20 or more units of monosaccharides, some may have hundreds or thousands of units. Monosaccharides, Oligosaccharides, and Polysaccharides are the main division of carbohydrates.
The most basic part of one’s diet is carbohydrates, as it is considered as one of the important sources of energy. Carbohydrates are the substances that yield aldehydes or ketones on hydrolysis. The common empirical formula among carbohydrates is (CH2O)n; some may also contain nitrogen, phosphorous, or sulfur. As the name suggests ‘carbohydrate’ is the word made up of three compounds which are carbon (C), hydrogen(H) and oxygen (O).
These serve as the fuel provider to the body, helping in the proper functioning of the brain and the whole body. Carbohydrates vary from the simple sugars like monosaccharides to the complex one. Monosaccharides are considered as the chief energy source, while polysaccharides act as the secondary energy reserve and in some, they form structural walls of cells.
Content: Monosaccharide Vs Disaccharide
Comparison Chart
Basis for Comparison | Monosaccharide | Polysaccharide |
---|---|---|
Size | Monosaccharide are the small sized compound of carbohydrates. | Polysaccharide are the large sized compound of carbohydrates. |
Molecular formula | Cn(H2O)n, where n is the small number varying from 2-10. | Cx(H2O)y, where x is usually a big number between 200-2500. |
Hydrolysation | Monosaccharide cannot be further hydrolysed. | Polysaccharide cannot be further hydrolysed as it contains 2 or more units of monosaccharide, which can be further broken down. |
Characters | Colorless, sweet in tastes, crystalline appearance. | Sweetness absent. |
Solubility | Soluble in water, but insoluble in non polar solvents. | Polysaccharide are insoluble in water. |
Made up of | They are the simplest unit of carbohydrates, made up of bonding between carbon, hydrogen and oxygen. | Polysaccharide are made up of numerous (several hundred) monosccharide units. |
Role | Monosaccharide are the chief energy source, which provide around 4 calories (kilo calories) per gram. | Polysaccharide are the structural component of cell walls and act as the energy reserves. |
Definition of Monosaccharide
As the name suggests, mono means ‘single’ and saccharin means ‘sugars’, hence these are termed as the simplest form of carbohydrates. They consist of one sugar unit which cannot be further hydrolyzed or broken down into simpler ones.
These are soluble in water but insoluble in nonpolar solvents. They are colorless, crystalline solids and are sweet in taste. These are unbranched carbon chains where all the carbon atoms are linked by single bonds.
The family of the monosaccharide consists of two members which are Aldoses and Ketoses. If the carbonyl group (when one of the carbon atoms of open-chain is linked by double bonds to any of the oxygen atoms) is at the end of the carbon chain than the monosaccharide is an aldose, but if the carbonyl group is at other position of the carbon chain than the monosaccharide is called as ketose. The other carbon atoms in the carbon chains have the hydroxyl group.
The simplest form of monosaccharides is trioses which are glyceraldehyde, an aldotriose, dihydroxyacetone and a ketotriose, consisting of three-carbon. Tetroses, pentoses, hexoses, and heptoses are the monosaccharides with four, five, six, and seven carbon atoms respectively in their backbone of structures.
All the monosaccharides occur in optically active isomeric forms as they contain one or more asymmetric (chiral) carbon atoms, except the dihydroxyacetone. They have their general formula is (CH2O)n, where n represents the number of carbon atoms present.
Monosaccharide appears in D and L form, where D stands for ‘Dextro’ form while L stands ‘Levo‘ form, these are the mirror images of each other. D-form is found in naturally occurring monosaccharides and L form is found in synthetically produced monosaccharides ones. These both forms have different properties.
Some common naturally occurring monosaccharides are Glucose, fructose, mannose, and galactose. Examples of foods that contain a lot of fruit juices, candies, sweet wines, honey, etc.
Definition of Polysaccharide
Poly means ‘many’ and saccharin means ‘sugar’ are the kind of carbohydrate, made up of ten to thousands of monosaccharides. Polysaccharides are also called as glycans. They are the long chains of monosaccharides units bonded together by glycosidic linkages which can be further hydrolyzed to give oligosaccharides or monosaccharides.
These are the polymers of high molecular weight. They differ from each other in the type of bonding, the length of the chains, recurring of monosaccharide units and degree of branching. Their structure varies from a linear to the highly branched chain. Glucose, galactose, fructose, and mannose are the few common polysaccharides.
These are the polymers of high molecular weight. They differ from each other in the type of bonding, the length of the chains, recurring of monosaccharide units and degree of branching. Their structure varies from a linear to the highly branched chain. Glucose, galactose, fructose, and mannose are the few common polysaccharides.
These are of two types Homopolysaccharides and Heteropolysaccharides. Homopolysaccharide contains a uniform species, it means all the monosaccharides units are of the same type. Whereas heteropolysaccharide contains two or more different type of monosaccharides units.
Examples are starch and glycogen, which are said as storage polysaccharides, while cellulose and chitin are said as structural polysaccharides.
- Cellulose: It is the most abundant carbohydrate found in nature. Cellulose is made up of glucose units, held together by beta-linkages. Cellulose is not digested by humans and animals, as they do not have the enzyme to break the beta linkages. Paper, microorganisms cotton and wood are the kind of cellulose.
- Arabinoxylans: These are found on the cell walls of plants.
- Chitin: Chitin forms the exoskeleton i.e. structural component or hard covering of many animals. Chitinases which is an enzyme catalyzes the reaction to break down the chitin, it is micro-organisms such as bacteria and fungi and some other plants.
- Pectins: These are present in non-woody parts of terrestrial plants and in primary cell walls.
Storage Polysaccharides
- Glycogen: It serves as secondary energy reserves in animals and fungus, after primary being the adipose tissue. It is made in liver and muscles or by glycogenesis in the brain and stomach. The chief source of carbohydrate in the animal body and yield glucose on hydrolysis.
- Starch: Starches are insoluble in water. Humans and animals can digest starch with the help of the enzyme called amylases. Potato, rice, wheat, and maize are the major sources of starch in the human diet.
We discussed the different kinds of polysaccharides present in nature, but among them, starch, cellulose, and glycogen are the main constituents in human nutrition.
Key Differences Between Monosaccharide and Polysaccharide
Following are the substantial key differences between monosaccharides and polysaccharides:
- Monosaccharides are the small sized compound of carbohydrates consisting of simple units of carbon, hydrogen, and oxygen; Polysaccharides are the largely sized compound of carbohydrates consisting of many monosaccharides units linked by glycosidic bonds.
- Molecular formula of monosaccharide is (CH2O)n, where n is the small number varying from 2-10 whereas Polysaccharides has Cx(H2O)y, where x is usually a big number between 200-2500
- Monosaccharides cannot be further hydrolyzed as it is present in it’s the simplest form, while Polysaccharides cannot be further hydrolyzed as it contains 2 or more units of a monosaccharide, which can be further hydrolyzed into oligosaccharides, or monosaccharide.
- A monosaccharide is colorless, sweet in tastes, crystalline appearance, the sweetness is completely absent in polysaccharide, though they are made from various units of monosaccharides, they can be homopolysaccharides or heteropolysaccharides.
- Monosaccharides are soluble in water, but insoluble in nonpolar solvents; whereas polysaccharide are insoluble in water
- Made up of the simplest unit of carbohydrates, which are carbon, hydrogen, and oxygen; Polysaccharides are made up of numerous (several thousand) monosaccharides units.
- Monosaccharides are the chief energy source of energy, which provides around 4 calories (kilocalories) per gram; Polysaccharides are the structural component of cell walls and act as the energy reserves.
Conclusion
All kind of macronutrient we take has its own biological value, they play their role very precisely. Each macronutrient breaks down into a smaller component in our diet. Carbohydrates which is also one of the macro nutrients play a vital role in our diet, as it is one of the main sources of providing energy to the body.
Sugars or saccharides are the compounds which contain two or more hydroxyl groups, with an aldehyde or ketone group. When two units of monosaccharides are joint to form a complex it is called disaccharides, while 3-10 complexed units are termed as oligosaccharides and 11 or more units joined together are called as polysaccharides.
Nader Farraje says
Really excellent effort.
thanks