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Unformatted text preview: Andrew Castleman 2/21/11 DNA Melting DNA is a double stranded, helical molecule formed from nitrogenous base pairs and a deoxyribose and phosphate backbone. The melting of DNA refers to the breaking of the hydrogen bonds between two complementary base pairs that results in two separate, single strands of DNA. Melting is most often a result of heating or a change in pH. When the DNA separates, it is subject to an effect known as the hyperchromic effect. This effect results from the freeing of the nitrogenous bases that are then able to absorb more light. The hyperchromic effect causes melted, single stranded DNA to increase in absorbance as compared to double stranded DNA. The increase in absorbance can be used to indicate the amount melted DNA. Once melted, if cooled rapidly, the DNA will form minimum interactions and should maintain a relatively melted state. The DNA molecule is a very negatively charged molecule. The phosphates of the backbone all repel each other and make melting easier. repel each other and make melting easier....
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- Spring '11