The nitrogenous bases that are present in DNA are purine and pyrimidine. The two pyrimidine bases present in DNA are cytosine and thymine. Pyrimidine is a heterocyclic aromatic organic compound. It is a six membered ring that contains four carbon atoms and two nitrogen atoms. Apart from cytosine and thymine, uracil is also a pyrimidine, but it is present in RNA.
Cytosine: contains an amine group and keto group at carbon-4 and carbon-2 position. Cytosine binds with guanine with a triple bond.
Thymine: contains a methyl group (CH3) in the place of the keto group that is at carbon-2. The anime group is present at carbon-4. Thymine bonds with adenine with double bond.
Biomolecules are the most essential organic molecules, which are involved in the maintenance and metabolic processes of living organisms. These non-living molecules are the actual foot-soldiers of the battle of sustenance of life.
There are four major classes of Biomolecules – Carbohydrates, Proteins, Nucleic acids and Lipids.