How does ethanol wash the DNA pellet?

Question

After the extraction of DNA by salt and isopropanol, ethanol is added to the pellet to purify the DNA. I suppose the ethanol does this by dissolving the salt and leaving the DNA. But how does that work and why does it happen?

Answer 1

The wash after precipitation is usually with 70% isopropanol.  The water dissolves the salt, but the high concentration of alcohol leaves the DNA as a precipitate (DNA is insoluble in alcohol).