Physico-Chemical Properties of Dna

Topics: DNA, Base pair, Nucleotide Pages: 5 (1504 words) Published: January 21, 2012
DNA, as we all know, is esteemed with the title of ‘Master Molecule ’. The three letters of DNA denotes of deoxyribonucleic acid .Now the thing that we ponder on is why DNA is so important to us. Why are the researchers & scientist persistently working on DNA? Why it is so important to know the tiniest details of DNA structure and function.?The simplest answer for “Why Is DNA Important?” is that DNA is the prerequisite for life’s inception. Firstly, it transfers hereditary information from generation to generation. Secondly, it controls the production of proteins. DNA even determines the structure of the cell, meaning whether it would be a nerve cell or eye cell etc. Our DNA seems to be ultimately responsible for the size, shape and function of every protein that our bodies make. Similarly, the DNA of each plant and animal seems to be ultimately responsible for the size, shape and function of every protein that each of them makes. We will now take a small overview on history, physical properties , chemical properties of DNA. Overview on History :

DNA was first isolated by Friedrich Miescher , who in 1869 discovered a microscopic substance in the pus of discarded surgical bandages that he called ‘NUCLEIN’ Finally in 1953, working together at the University of Cambridge in England, James Watson, an American scientist, and Francis Crick, a British researcher, made a major scientific breakthrough when they discovered the famous "double helix" - the structure of DNA, the molecule of life. In 2000 , a rough draft of a map of entire human genome was completed. In 2003,the final draft was completed .This information is being used to understand and function of disease. An interesting fact is If we unwrap all of the DNA of one individual’s body cell , we could reach the moon !

Physical Properties
In living organisms such as humans, DNA exists as a pair of molecules rather than a single molecule. These strands are entwined in the shape of a double helix and the helix is kept stable by hydrogen bonds, which can be found between the bases attached to the two strands. A long polymer, DNA is made up of smaller units called nucleotides. In turn, each nucleotide consists of a phosphate group, a sugar and a nitrogenous base. two helical chains each coiled round the same axis, and each with a pitch of 34 Å and a radius of 10 Å According to another study, when measured in a particular solution, the DNA chain measured 22 to 26 Å wide, and one nucleotide unit measured 3.3 Å (0.33 nm) long * Base Pairing

1.Base pairing is a defining property of DNA and was particularly exciting when it was first discovered because it suggested the 'copying' mechanism for DNA. 2.In DNA, bases are specific in that an adenine base, for example, only pairs with a thymine base. Following on that premise, a cytosine base will only bond to a guanine base. This base pairing is also known as complementary base pairing. * DNA Grooves

DNA has two kinds of grooves that play important roles in its functioning. 1. Major and minor grooves are structures to allow for necessary proteins in your body to make contact with bases. You might wonder what makes it so important for proteins to attach to the bases. * DNA Supercoiling

If you try to picture a rope, you can get a visual image of DNA supercoiling. 1.This coiling is a central property of DNA. DNA can be in a relaxed or coiled state and it is this coiling that allows our extremely long strands of DNA to fit or 'pack' into the comparatively much smaller cells in our bodies. * DNA Conformations

DNA can exist in different conformations and these are important for a range of DNA mechanisms. These conformations interact with enzymes in your body and are also involved in aspects such as DNA repair. * Temperature

As thermal energy increases, the frequency of hydrogen bonds breaking between the molecules...

References: * Alberts, Bruce; Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts and Peter Walters (2002). Molecular Biology of the Cell; Fourth Edition. New York and London: Garland Science.
* Wikipedia-
* Watson J.D. and Crick F.H.C. (1953). "A Structure for Deoxyribose Nucleic Acid" (PDF)
* T. M. Devlin 's Textbook of Biochemistry 7th (Seventh) edition(Textbook of Biochemistry with Clinical Correlations (Textbook of Biochemistry w/ Clinical Correlations) [Hardcover])(2010)
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