Describe the definition ,classification and function of carbohydrates.

Describe the definition ,classification and function of carbohydrates-Biochemistry :

Definition of carbohydrates:

The most abundant biomolecules on the earth is carbohydrate. They are primarily composed of the elements carbon , hydrogen and oxygen. The empiric formula for many of the simple carbohydrates is (CH2O )n,where n≤3.

 They can be defined as aldehyde or ketone derivatives of polyhydric alcohols.Most carbohydrates tests sweet and hence they are popularly known as sugar.

⏹️Classification of carbohydrates:

  There are three major size classes of carbohydrates: monosaccharides , oligosaccharides,and polysaccharides( the word saccharide is derived from the Greek Sakcharon, meaning"sugar".

Monosaccharides:

The basic building blocks (monomers) of all carbohydrates are monosaccharides. Monosaccharides are colorless, crystalline solids ,that are freely soluble in water but insoluble in nonpolar solvents.

The backbones of  common monosaccharides are unbranched carbon chains in which all the carbon atoms are linked by single bonds.

Based on the number of carbon atoms,they are known as trioses (3C), tetroses (4C),pentoses(5C),hexoses(6C).

Aldoses: These are the monosaccharides with an aldehyde group. Example: ribose(5C), glucose (6C).

Ketoses: These are the monosaccharides which have a keto group . Example: fructose (6C).

Five Important Monosaccharides,Image by-OpenStax College, Source, License-CC BY-SA3.0

Oligosaccharides:

 Carbohydrates composed of 2-10 monosaccharide molecules are known as oligosaccharides (Greek:oligo=few). In the oligosaccharides monosaccharide units are joined by characteristic linkages called glycosidic bonds.

Based on the number of monosaccharide units present,the oligosaccharides are further  subdivided into disaccharides and trisaccharides etc. Among the oligosaccharides disaccharides are the most abundant.

Sucrose is a disaccharide composed of two monosaccharides-glucose and fructose. Lactose is another oligosaccharide composed of glucose and galactose.

Branched oligosaccharides structure

Polysaccharides:

  Polysaccharides are sugar polymers containing more than 20 or so monosaccharide units:some polysaccharides have hundreds or thousands of units.

Most carbohydrates found in nature occur as polysaccharides . Polysaccharides are usually testless and form colloids with water. Polysaccharides are also known as glycans.
Also read:

1. How can glycolysis be regulated?
2. What is glycolysis? steps of glycolysis.
3. Best note ||For class11 ||Describe the structure of mitochondria in detail?
4. Best answer class 11|| TCA cycle.

The polysaccharides are of two types -homopolysaccharides and heteropolysaccharides. Homopolysaccharides are made up of single type of monosaccharide units . Example:starch , glycogen, cellulose.

Some homopolysaccharides serve as storage forms of monosaccharides that are used as fuels,starch and glycogen are homopolysaccharides of this type.

And the polysaccharides which are composed of two or more  different types of monosaccharides are known as heteropolysaccharides. Example: hyaluronic acid ,heparin.

Three Important Polysaccharides,Image by-OpenStax College,Source, License-CC BY-3.0

⏹️Functions of carbohydrates:

1.In the body carbohydrates are the main source of energy(4cal/g). Brain cells and RBC are almost fully dependent on carbohydrates for the energy.

2. Energy is stored in the form of carbohydrates in animals (glycogen)and plants (starch).

3. Carbohydrates are precursors for many organic compounds (fats,amino acids).

4. Excess carbohydrate is converted to fat.

5. Carbohydrates are also involves in the formation of part of the structure of the connective tissue of animals.

6. Carbohydrates also form part of the cell wall structures in bacteria and plants.

7. Carbohydrates are also involves in the formation of exoskeleton in arthropods.

8. Carbohydrates play a role in cell growth,cell to cell recognition, interaction and adhesion.

9.Ribose and deoxyribose sugars are part of the structural framework of RNA and DNA respectively.

➡️ If you like this post please share it.And visit this site regularly for more updates.