Nucleotides are the monomeric unit of nucleic acid; therefore, these are considered as polynucleotides. It is made up of three components i.e. nitrogenous base, sugar, and an ion of phosphoric acid. Nucleotides are phosphate easters of the nucleoside.

Friedrich Miescher first discovered nucleic acid from nuclei of pus cells from discarded bandages and called it nuclein. It was later revealed as a mixture of basic protein and phosphorus-containing acid, now called nucleic acid.

Uracil is considered like thymine, but it lacks methyl group at the C5 position. Uracil is a component of RNA whereas it is not found in DNA.

There are two types of nitrogenous bases in both RNA and DNA, purines and pyrimidines. Adenine and guanine are purines while cytosine and thymine come under pyrimidines.

The glycosidic bond formed between sugar and nitrogenous base during the formation of a nucleoside. This bond is held to be in β-configuration with respect to the ribose sugar leaving it’s base free to rotate around the bond.