Is DNA more or less soluble in alcohol (isopropanol) than in Water?

Answer 1

DNA precipitates in ethanol after you have added a salt because ethanol creates an electrostatic environment that allows the Na+ to bind to the PO3- groups on the sugar-phosphate backbone of DNA strands. Water has too high of a dielectric constant to allow a significant amount of the Na+ to bond.

Answer 2

Alcohols (ethanol and isopropanol most commonly) are used to precipitate DNA or total RNA from cell lysates because alcohols cause water to preferrentially form hydrogen bonds with them rather than the long-strand DNA or RNA molecules because interacting with smaller alcohol molecules increases the entropy of the system. The DNA and RNA will eventually have not enough water molecules to interact with and since they also cannot dissolve in alcohol, they precipitate out of solution. However the nucleic acids are still suspended because of their very small mass compared to the overall solution and centrifugation will be needed to collect the precipitated DNA or RNA into a pellet.

Answer 3

Alcohols (ethanol and isopropanol most commonly) are used to precipitate DNA or total RNA from cell lysates because alcohols cause water to preferrentially form hydrogen bonds with them rather than the long-strand DNA or RNA molecules because interacting with smaller alcohol molecules increases the entropy of the system. The DNA and RNA will eventually have not enough water molecules to interact with and since they also cannot dissolve in alcohol, they precipitate out of solution. However the nucleic acids are still suspended because of their very small mass compared to the overall solution and centrifugation will be needed to collect the precipitated DNA or RNA into a pellet.

Answer 4

Because it is.

Answer 5

no