Classification of Carbohydrates in Chemistry

Definition of Biochemistry: Biochemistry is the branch of chemistry that deals with the chemical processes occurring in living organisms.

The compound in living organisms

The different compounds in living organisms are 1. Carbohydrates 2. Proteins 3. Lipids 4. Vitamins 5. Enzymes.

Carbohydrates Definition 

Carbohydrates are defined as polyhydroxy aldehydes or polyhydroxy ketone or the molecules which yield these compounds on hydrolysis. Explanation- Carbohydrate is naturally occurring Organic compounds that occur mostly in plants however animals also contains a small amount of carbohydrate. 80% of the dry mass of carbohydrates while 1% of the mass of animals is due to carbohydrates.

Carbohydrates provide energy to the plants and animals but in plants, they are also structural materials which means that plants are made up of carbohydrates.  

Fundamentals of biochemistry

Sources of carbohydrates

Carbohydrate                                               Source

Glucose                                                        Grape, Sugar

Fructose                                                       Honey, Sugar

Starch                                                          Potatoes

Cellulose                                                     Wood

Glycogen                                                    Liver

Chemical Composition of Carbohydrates

Most carbohydrates have a general formula Cn (H2O)n. For example, glucose Ca(h2o)6. But some carbohydrates do not obey this formula. For example- 2-deoxyribose with a chemical formula of C5H10O4.

Classification of Carbohydrates

On the basis of a number of simple sugar units present per molecule, carbohydrates are divided into three major classes these are.

(I) Monosaccharides 

They are also called simple sugar. They contain only one sugar unit per molecule. They cants be broken down into more simple carbohydrates on hydrolysis. Exp. Glucose, Fructose

Subdivision of Monosaccharides:- The monosaccharides are again subdivided on the basis of the type of functional group and the number of carbon atoms in molecules. On the basis of the type of functional group monosaccharides may be classified as Ketoses, and Aliases.

Ketoses:- Ketoses are those monosaccharides that contain the functional group of ketones like fructose.

Aldoses:- Aldoses are those monosaccharides that contain the functional group of aldehyde like glucose. Monosaccharides can also be divided on the basis of the number of carbon atoms in the molecules.


For Example- Trioses, Tetroses, Pentoses, Hexoses, etc. Which contains 3,4,5 and 6 carbon atoms respectively.

(II) Oligosaccharides

These are those carbohydrates that contain 2-10 units of monosaccharides or simple units of monosaccharides or simple units per molecule.

Explanation:- Every oligosaccharide was broken down into two-to ten simple carbohydrates or monosaccharides upon acid hydrolysis. They can be further divided into disaccharides, trisaccharides, and tetrasaccharides respectively. 

Di-saccharides:- They produce two monosaccharides molecules upon acidic hydrolysis e.g. Maltose.

Tri-saccharides:- They produce three monosaccharides molecules upon acidic hydrolysis e.g. Raffinose. Upon hydrolysis produce a similar or different type of monosaccharides.

For Example:- maltose produces the same kind of two glucose units upon hydrolysis 

C12H22O11+H2O -----------------> 2C4H12O6

While sucrose produces two different types of monosaccharides e.g. Glucose and fructose upon hydrolysis.

C12H22O11+H2O ------------H+-----------> C6H12O6+C6H12O6

Glycoside Linkage or Bond

Glycoside link is ether functional group formed when two monosaccharides molecules react to produce a disaccharide.

Glycoside Linkage or Bond

Explanation:- During the reaction of two mono sacharide molecule, hydrogen atoms from one molecules and hydroxyl group form another molecules react they produce maltose through the formation of a glycoside link.

(III) Polysaccharides

Polysacharides are those carbohydrates which contains more than 10 monosacharides unit per molecules.

Explanation:- Polysacharides are the bio-polymersof monosacharides upon acid hydrolysis they produce more than 10 monosacharides molecules. EXP. 

(C6 H10 O5)n + nH2O --------H+-------> C6H12O

Structure of glucose

Function of Carbohydrates | Carbohydrates Used

Basic function of carbohydrate is the production of energy for the performance of vital activities in living organisms. Carbohydrates are also know as fuel of life. They produce energy by the process of oxidation.

Carbohydrate + O2 -------------------------> CO2+H2O+ Energy

Sources of Energy:

(i) Glucose:- Glucose is used as an immediate source of energy for sick and sportsmen. It is also used in the manufactore of jams and sweets.

(ii) Fructose:- Fructose in used as a sweetening agent in confectionery in medical syrup. It is also used to prevent sandiness in ice-cream. It is also used as a substitute of table sugar for the obese and diabetic.

(iii) Sucrose:- Sucrose is used as a food and ingredient of lams, jellies, confectioneries, syrup. It is also used in the preparation of sucrose octa-acetate which is used for the denaturation of alcohols and for making anhydrous adhesive.

(iv) Starch:- Starch is principally used as a food. It is industrially used for manufacturing of ethanol by the process of fermentation. It is also used as a stiffening agent in textile industry and in laundry. It is also used as an adhesive to fasten paper.

(v) Cellulose:- Cellulose has no food value but it is used as a roughage in our diet for promoting the peristaltic motion of digestive track. It is used for the manufacturing of paper. 


(vi) Receptors on cell membranes:- The receptors on the cell membranes are the complexes of carbohydrates with certain proteins. The receptors are involved in molecular targeting or molecular recognition.

(vii) Derivatives of Carbohydrates:- The derivatives of carbohydrates such as protein glycol heparin sulfate are involved in the attachment or adhesion of neurons to one adhesion of neurons to one another during the development of nervous system.

Role of various Carbohydrates in Heath & Diseases

The are different types of carbohydrate which are involved in the heath and disease of living beings some of these are given as under.

Sucrose:- Sucrose is a disaccharides since long, it has been used as a sweetening agent and as a source of production of energy for living organism.

Negative health  Affect:- Use of sucrose is the primary cause of tooth decay and obesity.

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Classification of Compounds in Chemistry

Chemistry fundamentals

Type of Solution on the basis of Solubility | Concentration of Solution | Percentage of Composition


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