Nucleotides are the basic units of nucleic acids (DNA and RNA). Nucleic acids are biomolecules essential for all forms of life.
A nucleotide has 3 components:
1. Pentose sugar
2. Nitrogenous base
3. Phosphate sugar
It is a monosaccharide with 5 carbon atoms. It forms the backbone of polynucleotide chain. It is also of 2 types.
1. Ribose sugar (which is present in RNA).
2. Deoxyribose sugar (Which is present in DNA).
In ribose sugar, at 2’ position OH group is present and in Deoxyribose sugar, at 2’ position only H is presence. Pentose sugar only decides whether the nucleic acid formed is Deoxyribonucleic acid or Ribonucleic acid.
Phosphate Group :
Phosphate group is an organic salt of Phosphorus. It forms back bone of polynucleotide chain along with sugar.
Nitrogenous base is a compound that contains nitrogen and has the chemical properties of base.
There are two types of nitrogenous base:
Purines: Purines are heterocyclic aromatic organic compound. It is a 9 membered double ring containing 4 nitrogen and 5 carbon atoms.
Examples: Adenine and Guanine
Pyrimidines: Pyrimidines are also heterocyclic aromatic compound but unlike purine it is a 6 membered chain containing 2 nitrogen and 4 carbon atoms.
Examples: Cytosine, Uracil and Thymine
FLOW CHART OF STRUCTURE OF A NUCLEOTIDE