Genetic Material

This is a chemical substance in which genetic information is coded. The necessary information for creating the symptoms which are controlled by a gene is called genetic information.
The genetic information is preserved in DNA in the form of nitrogenous bases and the group of nitrogenous bases form of a gene.

Nitrogenous Bases 
There are following two types-

  • Purines:- Adenine and guanine are purine.
  • Nitrogenous waste:- These are found in both DNA & RNA. Adenine is denoted by "A" and Guanine is denoted by "G".
  • Pyrimidine:- Thymine is  denoted by "T" and Cytosine is denoted by "C" and Uracil is denoted by "C" 
    NCERT

  • In RNA Uracil is found at the place of Thymine.
  • Thymine is bonded with Adenine with the help of two hydrogen bonds.
  • Guanine is bonded with Cytosine with the help of three hydrogen bonds.
  • Nitrogenous bases are attached with pentose sugar by a glycosidic bond, the phosphate group {H3PO4} at the end of the phosphoester bond.

Nucleoside 

A single nucleoside is formed by the composition of nitrogenous bases with a pentose sugar.

Nitrogenous bases + Pentose sugar = Nucleoside

A nucleoside is following four types:-
  1. Adenosine= Adenine+Deoxyribose sugar
  2. Guanosine= Guanine+Deoxyribose sugar
  3. Cytidine= Cytosine+Deoxyribose sugar
  4. Thymidne= Thymine+Deoxyribose sugar

Nucleotide

Nitrogenous bases, a pentose sugar, and a phosphate group{H3PO4} form a unit of nucleotide. This phosphoric acid merged with nucleoside then formed a unit of nucleotide.

Nucleotide= Nucleoside + phosphate group 
Nucleotide= nitrogenous bases+ pentose sugar+phosphate group

Following four types of nucleotides are formed in DNA:-
  1. Deoxy Adencylic acid = Adenosine+phosphate group
  2. Deoxy Guancylic acid = Guanosine+ phosphate group
  3. Deoxy Thymidylic acid= Thymidine+phosphate group
  4. Deoxy Cytidylic acid= Cytidine+phosphate group

Formation of Poly Nucleotide Chain:-

The two nucleotide chains of DNA attached with hydron bonds phosphodiester bond, from the end 3' to 5' formed in dinucleotide formed polynucleotide Chain, In which two polynucleotide chains found in opposite direction with each other or one chain is towards 3' to 5' direction and another chain is 5' to 3' direction. In which at the end of 5' of the sugar-phosphate group while the end of 3' end has a hydroxyl group (-OH).
In the polynucleotide chain, sugar and phosphate make the basis of  DNA that is called the sugar-phosphate backbone.