Dna and Rna

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DNA AND RNA |

DONE BY : FATIMA SHAFIQUE |

ID no: 201420060 |

COURSE TITLE: General Science |

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Introduction

DNA molecule is a hereditary material which is transmitted from generation to generation. It is the largest molecule in the living cell comprising of several millions of nucleotide chain. It is in the sequence of nucleotides in the polymers where genetic information carried by chromosomes is located. Each nucleotide is composed of three parts: nitrogenous base like purine and pyrimidine, a sugar (deoxyribose) and a phosphate group. The nitrogenous base determines the identity of the nucleotide. RNA is a nucleic acid having almost similar structure as that of DNA molecule except a uracil base instead of thymine. There are three different species of RNA. All these are essential in the normal functioning of the cell especially in protein synthesis. RNA molecule is not the information carrier excepting in few viruses. Moreover these molecules are less stable compared to DNA molecule

Deoxyribonucleic Acid (DNA):

Watson and Crick in 1953, discovered the 3-dimentional model of DNA molecule and postulated that it consist of two helical strands wound around the same axis forming a right handed double helical structure. The hydrophilic backbone of alternating deoxyribose and phosphate groups are on the exterior of the double helix facing the surrounding aqueous media. The purine and pyrimidine bases of both the strands are stacked in the interior of the double helix, with their hydrophobic bases forming nearly planar ring structures very close together and perpendicular to the long DNA axis. The pairing of the two strands form major and the minor grooves on the surface of the duplex. An individual nucleotide base of one strand is paired with the same plane with base of the other strand. The vertically stacked bases inside the double helix is around 3.4Å apart and 34Å constitutes a full complete turn bearing...