Question

What is the reason of adding wash buffer twice while purifying DNA and why it is diluted with 100% Ethanol?

Answer 1

A) Reason of adding wash buffer twice while purifying DNA :

1) When we put the cellular components into a centrifuge column to remove the DNA, then DNA binds to membrane across the column and the proteins and other components in cytoplasm will pass through. This is achieved by adding washing buffers as well as ethanol.

2) Upon centrifugation, the material will pass through the membrane and attract DNA thst allow debris to pass through by washing buffer.

B) It is diluted with 100% Ethanol :

DNA is insoluble in alcohols, so we use 100% alcohols for precipitation which means for purifying DNA.

70% ethanol remove the excess of salts that are dissolved in the 30% of water.

70% ethanol dissolve the DNA in 30% water in which extracted DNA interfere during purification.