How is the structure of DNA organized? What is the biological significance of DNA?

Explanation

Structure of DNA:

Watson and crick model of DNA:
(i)DNA molecule consists of two polynucleotide chains.
(ii)These chains from a double helix structure with two strands which run anti-parallel to one another.
(iii)Nitrogenous bases in the centre are linked to sugar-phosphate units which from the backbone of the DNA.
(iv)Pairing between the nitrogenous bases is very specific and is always between purine and pyrimidine linked by hydrogen bonds.
Adenine(A)links tymine (T)with two hydrogen bonds (A=T)
Cytosine (C)links Guanine (G)with three hydrogen bonds `(C-=G)`
This is called complementary base pairing
(v)Hydrogen bonds of the double helix is 34 `A^(@)` (3.4 nm).There are ten base pairs in a complete turn.
(vii)The nucleotides in a helix are joined together by phosphodiester bonds.
Significane of DNA:(i)It is responsible for the transmission of hereditary information from one generation to next generation.
(ii)It contains information required for the formation of proteins.
(iii)It controls the developmental process and life activiteis of an organism.