L34_nucleicacids2_462a_2013

The reason that the double helix to random coil

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Unformatted text preview: ectrostatic repulsion of the backbone phosphates than in the duplex (double-stranded form). Enthalpic effect. ΔSconformational Conformational entropy (one molecule --> 2 molecules, & more freedom of single strands to adopt different conformations in solution). Also favored by hydrogen bond formation with water. Note!: Base pairing by H-bonding provides all the specificity required for the complementarity of the 2 strands, essential for the processes of DNA replication and transcription. Factors promoMng denaturaMon/melMng of DNA Free energy change for the double helix random coil transition is ΔG = ΔH – TΔS. ΔHelectrostatic (relief of charge repulsion) is negative and ΔSconformational is positive, both favorable for strand separation/ unfolding. The reason that the double helix to random coil transition is unfavorable under physiological conditions is that there is a large positive ΔH associated with disrupting the base-stacking int...
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This test prep was uploaded on 02/25/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Spring '08 term at University of Arizona- Tucson.

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