RNA is one of two nucleic acids found in organisms such as animals, plants, viruses and bacteria. It is composed of four different types of building blocks called nucleotides. Therefore, it must have certain properties (ie super winding) through which it can be conveniently housed in the cell. It is much more abundant in eukaryotes than in prokaryotes. The purine bases and pyrimidine both strands are stacked inside the double helix, their hydrophobic bases forming almost planar annular structures very close to each other and perpendicular to the long axis of the DNA.ĭeoxyribonucleic acid (DNA) is a macromolecular molecule complex structurally and functionally present in various organisms. The hydrophilic skeleton groups of deoxyribose and phosphate alternate is located outside the double helix opposite the surrounding aqueous media. Watson and Crick, in 1953, discovered the three-dimensional model of the DNA molecule and postulated that it consisted of two helical strands wrapped around the same axis forming a helical double-helical structure. Further explanations about their structure and functions are given in the following pages. In addition, these molecules are less stable with respect to the DNA molecule. The RNA molecule is not the information carrier with the exception of a few viruses. All these elements are essential in the normal functioning of the cell, especially in the synthesis of proteins. There are three different species of RNA.
RNA is a nucleic acid having a structure almost similar to that of the DNA molecule except one base of uracil instead of thymine. The nitrogen base determines the identity of the nucleotide. It is in the sequence of nucleotides in polymers that genetic information carried by chromosomes is found.Įach nucleotide is composed of three parts: nitrogenous base like purine and the pyrimidine, a sugar ( deoxyribose ) and a phosphate group. It is the largest molecule of the living cell composed of several million nucleotide chains.
The DNA molecule is a hereditary material transmitted from generation to generation.
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