Nucleic Acid

Nucleic Acids

Nucleic acids are high molecular weight biopolymers with mononucleotides as their repeating units.  They are chains of five membered ring sugars linked by phosphate group. The anomeric carbon of each sugar is bonded to a nitrogen of a heterocyclic compound in a β-glycosides linkage.

Nucleosides

The nucleosides are compounds in which nitrogenous bases (purine and pyrimidines) are conjugated to the pentose sugars (ribose and deoxyribose) by β–glycosidic linkage.

Nucleotides

Nucleotides are the phosphoric acid esters of nucleosides.  These exist either in the free form or as subunits in nucleic acids. A nucleotide is a nucleoside with either the 5’ or 3’-OH group bonded in ester linkage to a phosphoric acids. The nucleotides of RNA (where the sugar is D-ribose) are more precisely called ribonucleotides, while the nucleotides of DNA  (2’-deoxy-D-ribose) are called deoxyribonucleotides.