Purifying DNA from a cheek swab generally involves a few key steps. Here are four commonly used steps in the process:
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Cell Lysis: The first step is to break open the cells in the cheek swab to release the DNA. This usually involves adding a lysis buffer, which contains detergents and enzymes (like proteinase K) that disrupt the cell membrane and break down proteins.
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Separation of DNA: After lysis, the mixture contains DNA, proteins, and cellular debris. To separate the DNA, you may need to add a salt solution to precipitate proteins and other impurities out of the solution. Following this, the mixture is often centrifuged to separate the solid material from the liquid containing the DNA.
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DNA Precipitation: The next step involves adding alcohol (usually ethanol or isopropanol) to the supernatant containing the DNA, which causes the DNA to precipitate out of the solution. The solution is again centrifuged to collect the DNA, which forms a pellet.
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Washing and Resuspension: The DNA pellet is then washed with a cold alcohol solution to remove any remaining impurities. Finally, the DNA is dissolved in a buffer solution (such as TE buffer or nuclease-free water) for storage and further use.
These steps can vary slightly based on the specific protocol or kit being used, but they generally outline the process of purifying DNA from a cheek swab.