Isolation of DNA is one of the prime processes carried out in any research or experiment involving analysis of DNA. Extraction of DNA is not a very cumbersome process as many amateurs may think but rather simple and logical. I found this process to be exciting too when I first thought about isolating the molecules that have all the information about who you are.
I thought commenting on the basic aspects of isolating DNA from a bunch of cells rather than going through detail into the exact steps, since any site specifying DNA isolation protocols could deliver it. Many advanced and economically favorable processes exist for quick and pure isolation of DNA. However, the principles are more or less the same and almost always involve some basic principles.
Well, the first step obviously would be to eliminate everything in your way to get to your DNA. So initially the cell membrane and the nuclear membranes are broken up which is known as cell lysis followed by exposure of DNA within. Several methods are used to achieve this but its always possible to use some of your kitchen skills. Wonder how that’s done? It’s simply called grinding.
Now you have a soup of molecules containing DNA, cellular proteins, membrane lipids and all sorts of other macro molecules. Let’s remove each of them one by one. First goes the lipids, you can easily remove the lipids by adding a detergent. As you all know detergents are an effective way of removing non polar impurities that are insoluble in water. One of the most commonly used detergent is SDS (Sodium Doedecyl Sulfate).
Next we move on to removing proteins. Proteins could be digested off easily by enzymes called proteases which yield soluble products (peptides and amino acids).
Most often RNA is eliminated by treating with RNase. RNA is the most resembling molecule to DNA which makes it highly possible for it to often contaminate during DNA preps.
All’s done now and finally it is essential to aggregate DNA or rather crudely, visualize it. Alcohols are used for this purpose. DNA is insoluble in alcohol and upon addition, a pellet appears which is actually a large ball of hugely concentrated DNA. Several pellet washings are done with alcohol to remove impurities and ions. Well now you got your DNA whats next? The answers are endless and depends upon the purpose of your extraction.