Step by step guide to extracting your DNA from your spit
Materials Required:
- 1 Shot glass
- Several Drops of Dish Soap – must contain sodium laurel sulfate
- 1 pinch of salt
- Contact lens solution OR meat tenderizer OR pineapple juice (optional)
- Ice-cold 120+ proof liquor (that’s 60% plus – Bacardi 151 should be sufficient)
Step 1: Spit into the shot glass
-Rub the inside of your cheeks and rub your tongue around. Try and fill at least 1/4 of the glass with spit. This is harder than it sounds! Think about bacon.
Why are we doing this?
Spit contains cells from your mouth and cells contain DNA. This is the same DNA that is in every cell in your body (except for those pesky microbes that are all over the place).
Step 2: Add the dish soap
- Mix it around gently
Why are we doing this?
Dish soap causes the cells in your spit to lyse (aka die, break open, explode). Once they lyse, the DNA is released into the spit, just waiting for us to find it.
Step 3: Add Contact Lens solution, Meat Tenderizer or Pineapple Juice
-Give it a gentle stir
Why are we doing this?
All three of those ingredients contain protease – enzymes which break down proteins. Since we just lysed the cells, everything in them is floating around, including proteins. To help extract the DNA we will break down some of these proteins using protease.
Step 4: Add the pinch of salt
- Give it a gentle stir
Why are we doing this?
DNA is a negatively charged molecule. To help it precipitate we add salt (which forms Na+ and Cl- ions in water). The Sodium (Na+ ions) will be attracted to the DNA.
This is important because we are trying to gather a large amount of DNA in one place. If they are negatively charged they will repel each other. If the negative charge is matched by a positive charge (the Sodium ions) it will make it much easier for the DNA to gather together.
Step 5: Fill the rest of the shot glass of alcohol
-You must be VERY careful in this step to pour the alcohol on TOP of the spit and not let it mix. You can do this by pouring it down the side of the glass very gently and slowly. Note: you must have steady hands, so no drinking the alcohol beforehand.
Why are we doing this?
DNA is very insoluble in alcohol, so the DNA at the surface of the spit precipitates out. As this happens, DNA deeper in the spit solution gets drawn up and also precipitates.
Step 6: Look at it!
- In the alcohol you should see a white cloudy mass, this is your DNA. Apologies, you cannot actually see the helix.
You’re done!
Reference: http://www.instructables.com/id/5-minute-DNA-Extraction-in-a-Shot-Glass/
