Cell biology Bio201
What are carbohydrates?write down the classification of carbohydrates and function of each class with example?
Carbohydrates are polyhydroxy,aldehydes or ketones.Carbohydrates are biomolecules consisting of carbon,hydrogen,and oxygen atoms.The ratio of hydrogen and oxygen is 2:1.Carbohydrates have a empirical formula Cn(H2O)n.The number of carbons may be from three to many thousands.Insoluble carbohydrate polymers serves as structural and protective elements in the cell walls of bacteria and plants and in the connective tissues of animals.Carbohydrates are found in a wide variety of foods.The impotant sources are cereals,potatoes,sugarcane,fruits,mlik,and etc.
Classification of carbohydrates:
Carbohydrates are classified into followig groups.
1. Monosaccharides. 2. Polysaccharides.
3. Oligosaccharides. 4. Disaccherides.
The word saccharide is derived from a Greek word sakcharon.It means sugar.Saccharide is used as a unit of carbohydrates.
Monosaccharides are simple sugars.It is the simplest form of carbohydrates. They are basic unit of carbohydrates.The general formula of monosaccharide is CH2O.They contain carbon number from three to seven.Monosaccharides show following characteristics:
1. They are sweet in taste.
2. They are easily soluble in water.
3. In aqueous solutions, most monosaccharides form rings.
4. Monosaccharides are major nutrients of cells. They are broken down during cellular respiration to release energy.
Types of Monosaccharides
There are following types of monosaccharides:
A monosaccharide which have three carbon atom.Trioses are important in respiration.
They have four carbons.Tetroses are rare in nature.They occur in some bacteria.
Pentoses. They have five carbons.Ribose sugar is a pentose. It is an aldo sugar.It is present in ribonucleic acid.
Hexoses.They have six carbons.For example,glucose,fructose.
Functions of Monosaccharides.
Glucose is a carbohydrate that is metabolized with in cells to produce energy.In the presence of oxygen, glucose breaks down into carbon dioxide and water ,and energy is released as a byproduct.
2. The ribose and deoxyribose monosaccharides are vital elements of RNA and DNA which are building blocks of life.
Examples of Monosaccharides
Glucose and fructose.
The polymer of many monosaccharides is called polysaccharide.Polysaccharides are complex carbohydrates, composed of 10 to several thousand monosaccharides.
Types of polysaccharides
When all the monosaccharides in a polysaccharide are same type the polysaccharide is called a homopolysaccharide
When more than one type of monosaccharides is present then it is called hetropolysaccharides.
Examples of Polysaccharides
It is found in fruits, grains and seeds .The monomers are linked by 1-4 linkage in starch. Starch has two types amylase starch,amylopectin.
It is a simple form of starch.Amylose have unbranched chain of glucose.
It is most complex form of starch. It have branched chain.
Cellulose,and Chitin are the examples of polysaccharides.
Function of Polysaccharides.
Polysaccharides like starch store energy.Some polysaccharides like chitin,cellulose play a vital role in life
The sugars composed of two monosaccharides are called disaccharides.The two monosaccharides are held by a covalent bond.
Sucrose,lactose and maltose.
Function of disaccharides.
Disaccharides are found in our food.It is added as a sweetener in sweet food.
Oligo is a Greek word which means few and saccharide mean sugar.So,oligosaccharide is a sugar which contains a small number of monosaccharides.
Function of Oligosaccharides.
Oligosaccharide have many functions it has the ability of cell binding. For example glycolipids have an important role in immune system.