Nucleosides (Nucleic Acids)

2.11.4 Nucleosides (Nucleic Acids)

These naturally occurring substances are of prime biological importance and essentially possess three vital components namely: first, a sugar moiety e.g.; ribose or 2-desoxyribose; secondly, a purine or pyrimidine base e.g.; adenine, guanine and cytosine; and thirdly, a phosphoric acid. A base-sugar unit is known as a nucleoside, whereas a base-sugar phosphoric acid unit is known as nucleotide. An example of a nucleotide and a nucleoside is given here under:

Nucleotide : An odenylic acid unit of RNA

Nucleoside : Adenosine with the adenine as the heterocyclic base.

Source:Pharmacognosy And Pharmacobiotechnology By Ashutosh Kar