Why is cold water better than warm water for extracting DNA?
Cold water helps keep the DNA intact during the extraction process. How? Cooling slows down enzymatic reactions. This protects DNA from enzymes that can destroy it. Why would a cell contain enzymes that destroy DNA? These enzymes are present in the cell cytoplasm (not the nucleus) to destroy the DNA of viruses that may enter our cells and make us sick. A cell’s DNA is usually protected from such enzymes (called DNases) by the nuclear membrane, but adding detergent destroys that membrane.
