Question

What are the 4 steps of DNA extraction?

Answer 1

The three basic steps of DNA extraction are 1) lysis, 2) precipitation, and 3) purification.

Step 1: Lysis

In this step, the cell and the nucleus are broken open to release the DNA inside and there are two ways to do this. First,  mechanical disruption  breaks open the cells. This can be done with a tissue homogenizer (like a small blender), with a mortar and pestle, or by cutting the tissue into small pieces. Mechanical disruption is particularly important when using plant cells because they have a tough cell wall. Second,  lysis  uses detergents and enzymes such as Proteinase K to free the DNA and dissolve cellular proteins.

Step 2: Precipitation

When you complete the lysis step, the DNA has been freed from the nucleus, but it is now mixed with mashed up cell parts. Precipitation separates DNA from this cellular debris. First, Na+ ions (sodium) neutralize the negative charges on the DNA molecules, which makes them more stable and less water soluble. Next, alcohol (such as ethanol or isopropanol) is added and causes the DNA to precipitate out of the aqueous solution because it is not soluble in alcohol.

Step 3: Purification

Now that DNA has been separated from the aqueous phase, it can be rinsed with alcohol to remove any remaining unwanted material and cellular debris. At this point the purified DNA is usually re-dissolved in water for easy handling and storage.