DIY: Extracting Strawberry DNA

10 October 2017

Interview with

Jonathan Lawson, University of Cambridge

What exactly is DNA and what does it look like? Jonathan Lawson from the Babraham Institute near Cambridge, has an experiment you can try at home... 

Jonathan - DNA is the instruction manual for every living thing. In every human cell there’s about two metres of DNA; what it is series of chemical units called bases which are joined together in a long chain which is what makes the helix structure. There’s four different chemical units A, C, G, and T, and the order of those is how information is stored.

So now we’re going to extract some DNA from some strawberries and we’ve come to the Old Cavendish Laboratory in Cambridge, which is where DNA was first worked out by Watson and Crick in 1953.

We’re going to take some strawberries, put the strawberries in a plastic sandwich bag, and then to that you want to add a little bit of salt, some water and, finally, some washing up liquid. Then basically with you hands you’re going to squish the strawberries as much as you can so that all of the DNA gets released from the cells, and there you have a nice, fairly clear red liquid, but you can’t see the DNA in this form.

The way you visualise it, the way you get to have a look at it, is to make lots and lots of DNA stick together so that they’re then thick enough, in clumps, to be able to see them. And the way you do that is by adding some alcohol. Now when you look you’ll see very thin, furry white strands and that’s the DNA all clumped together. And all the genetic information that was needed to make strawberries is in those clumps of white DNA.

Although what we’ve done just here is quite a simple experiment that you can easily do in the kitchen, exactly the same procedure - a detergent to break open the cells, salt to protect the DNA, and alcohol to separate the DNA from the rest of the cells is exactly the same thing that happens in labs all over the world right now when they are sequencing DNA and looking to understand genes and the genome

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