Structure of Nucleic Acid

Introduction: As discussed in previous lecture, genetic material of the organism controls the biological processes. Most of the organism (prokaryotic/eukaryotic) has DNA as the genetic whereas a minor fraction (virus etc) has RNA as genetic material. DNA or RNA is the biopolymer and is acidic in nature. In eukaryotic cells (animal or plant), nucleic acid is present within the nucleus whereas in prokaryotic cells, it is present as free form in the cytosol. The first nucleic acid was isolated by friedrich miescher in 1868. In the present lecture, we will discuss the structure of nucleic acid, its composition and other salient features. Understanding these properties will led us to understand the process of replication, transcription and translation (Discussed in later lectures).   

Composition of nucleic acid: The nucleic acid (DNA or RNA) is composed of 3 components; (1) phosphoric acid, (2) base and (3) sugar. The phosphoric acid provides the backbone to the polymer where as sugar work as anchoring point for nitrogenous bases. The 9 membered nitrogenous bases give the diversity in the sequence of nucleic acid (Figure 26.1). The detail description of the individual component is as follows:

Phosphate backbone: Phosphoric acid serves as backbone of the molecule.

Figure 26.1: Components of Nucleic acid.