DNA is made up of three types of compounds viz. –
(A) Phosphoric acid
(B) Pentose sugar
(C) Nitrogen bases
(A) Phosphoric acid (H3po4)
It occupies the peripheral region of the DNA molecule. It is attached to the 5th carbon of sugar molecule of its own nucleotide in the form of phosphate group. It get attached to the 3rd carbon of the sugar of adjacent nucleotide. It is called as phosphodiester bond.
(B) Pentose Sugar:
It is deoxyribose type in DNA. Which has one oxygen atom less at carbon number 2. The first and fourth carbon atoms unite with a oxygen to form a ring.
(C) Nitrogen base:
They are of two types-
(a) Purines – They are double ring (one hexa & one penta) compounds. They are of two types viz. – Adenine (A) and Guanine (G).
(b) Pyrimidines – They have one hexa ring. They are of two types in DNA viz. – Cytosine (C) and Thymine (T)
