Question

role of isopropanol and ethanol in dna extraction

Answer 1

Since DNA is insoluble in ethanol and isopropanol, the addition of alcohol, followed by centrifugation, will cause the DNA proteins to come out of the solution. When DNA concentration in the sample is heavy, the addition of ethanol will cause a white precipitate to form immediately.


here is the complete answer.

DNA is less soluble in isopropanol so it will fall out of solution faster and at a lower concentration, but the downside is that the salt will too. With ethanol, the DNA needs to be at a higher concentration to flocculate but the salt tends to stay soluble, even at cold temperatures.

DNA falls out of solution in 35% isopropanol and 0.5 M salt. Using ethanol, the final concentration needs to be around 75% with 0.5 M salt. So for the typical precipitation protocol, isopropanol is added from between 0.7–1 volumes of sample and ethanol is added at 2-2.5 volumes of sample.