| | Re: DNA Nucleic Acid Precipitation
Water has a high dielectric constant, ethanol has a much lower constant. Therefore, when you add ethanol to water, the overall dielectric constant of the solution is lowered. What this does is lower the strength of hydration shells around polar molecules "dissolved" in solution. When you add cations (Li, Na, etc) they will ionically bond to the negatively charged phosphate backbone of DNA (because the hydration shells created by water are weakened due to addition of ethanol), thus precipitating the molecule out of solution.
Hope this helps.
Last edited by gel; 02-25-2009 at 10:44 PM.