DNA is the abbreviation for deoxyribonucleic acid, which contains genetic information about the functioning and development of all living organisms and is responsible for their transmission. DNA is a molecule unique to living beings, and is therefore considered a molecule of life. In non-living matter there is no DNA, for example, a stone does not contain this molecule.
The DNA is found in the nucleus of the cells of living beings and contains all the genetic information of the cell. Genes, molecules that transmit the characteristics of biological inheritance from parents to children, are fragments of DNA separated into chromosomes, which code for the shape of the body, the color of the eyes and hair, etc.
In genetic studies, forensics and molecular biology experiments, DNA extraction is very common. For these professional genetic studies special protocols are needed, but with the products we have at home we can easily extract the DNA. Do you dare to extract your DNA from your saliva?
WHAT DO WE NEED?
Believe it or not, DNA extraction can easily be done with the things we have at home:
- Dishwashing liquid soap
- 96º of cold alcohol (put in the freezer before DNA extraction)
- Mineral water
- Clear Glasses
- 1 spoon
STEP BY STEP
- Prepare the necessary solutions for DNA extraction. The first thing you have to do is to prepare the two solutions that appear in the following lines:
● Salt water. Mix in a recipient 10 spoonfuls of mineral water (200-250 ml approx.) and one spoonful of common salt, stir until it dissolves.
● Soapy water. Mix in another recipient 3 spoonfuls of water mineral and one spoonful of liquid soap to clean the recipients, mix slowly without foaming.
- Biological sample needed for DNA extraction. You will use saliva to extract your DNA. With a little mineral water (a couple of tablespoons), you will clean your mouth for 45-60 seconds, as in the shakes you make when you brush your teeth. After this time, pour the mouth water + saliva into the recipient with which you will extract the DNA.
3. Mix the DNA extraction sample with the solutions we have prepared. Add one tablespoon of the solutions you have prepared to the recipient in which you have placed the water + saliva. That is, in the container in which the DNA extraction sample is placed, add one tablespoon of saltwater and one tablespoon of soapy water. Mix the contents of the container well but slowly (so as not to cause foam).
- Add alcohol to the DNA extraction sample cup. The next step is to add the alcohol that you have left to cool in the freezer (approximately twice the volume of the contents that you have finished in the cup). It is very important that this alcohol is poured slowly down the walls of the glass so that it does not mix with the contents in the container. In this way, the content present in the recipient will be divided into two layers and in this separation between the mixing layer and the layer of alcohol the DNA will be precipitated.
- Precipitation of DNA. After letting the contents of the container rest for a few minutes, you will see the small threads or whitish fibers appear in that interface, it is your DNA. If you let it sit longer, your DNA will rise to the surface (not always). With a toothpick, you can easily pull out your liquid DNA.
When the sample is mixed with soapy water, the cell membranes that are in the saliva break down because the soap dissolves fats or lipids (this is the same principle that soap uses to clean the oil from our skin). Fat is the main component of the plasma and nuclear membranes of the cells, so when the membranes break, the DNA comes out. The addition of water with salts reduces the solubility of proteins, which facilitates their separation from DNA. In this way, your DNA will precipitate more “clean”.
The molecule that tends to bind DNA is very long, which is why it is so easy to observe the accumulation of cellular DNA through evidence. The DNA molecule dissolves in water and is isolated by precipitating in alcohol. That’s why the coils formed by your DNA begin to show up at the interface between the mixture and the alcohol. The alcohol separates the DNA from other cellular components that remain in watery solution.