5 minute DNA Extraction in a Shot Glass

Step 5Pour on a layer of the rum

Pour on a layer of the rum
Mix the solution in the shot glass for a minute by gently shaking and rocking the glass.

Now gently add a layer of the overproof rum to fill up the shot glass. The best way to do this is by tilting the shot glass and transferring the rum over a little bit at a time using a straw. If you have a steady hand, however (or just think you do, like me), you can try and slowly pour the icy-cold rum from the bottle onto the top of the saliva in the shot glass. The key thing here is to prevent the alcohol from mixing much past the surface of the saliva.

You should see some cloudy, snot-like white stuff suddenly appear near the boundary between the saliva and alcohol as you add the alcohol. This is DNA (and probably a lot of other cellular junk) precipitating out of solution!

What's going on? DNA is not very soluble in alcohol, so some of the free DNA at the surface of the saliva solution immediately precipitates when we begin to add the alcohol. Other, deeper DNAs are pulled out of solution by the precipitating DNAs into the alcohol, and suddenly we end up with this visible floating mass of DNA. You can see the precipitate in the second photo.
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2 comments
Feb 2, 2009. 9:41 AMkid123 says:
you can do this with rubbing alcohol
Feb 23, 2009. 1:52 PMstonehenge360 says:
yes but drinking rubbing alcohol will kill you
Nov 23, 2009. 1:25 AMzhou777 says:
yes, but you don't have to drink it. 

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Author:macowell
I am passionate about amateur biotechnology and more generally what is called Citizen Science. After graduating with a degree in Biology from Davidson College, I worked at MIT coordinating the Intern...
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