Ever wanted to extract DNA from your own cells? Possibly not but you should! This is a great experiment to get children talking about DNA, cells and the human body, plus it’s a bit gross so will be popular with kids.

You will need:

• Clear shot glass/similar small clear glass
• Sports drink
• Salt
• Pineapple juice
• Rubbing alcohol (at least 70%) – ice cold works best.
• Washing up liquid
• Cocktail stick
• Cup

Method:

• Swill a little sports drink around your mouth for at least 1 minute and spit it into a cup. Pour some of this mixture into your shot glass until it is around 1/3 full. This removes cells from your cheeks but don’t worry, your body is constantly making new cells.
• Add a pinch of salt, a squirt of washing liquid and a few drops of pineapple juice – these all help to break down the cells and release the DNA.
• Mix gently with a cocktail stick but try not to mix so fast you make bubbles
• Pour alcohol very slowly down the side of the glass so that it creates a layer on top of the sports drink mixture.
• Look at the shot glass from the side – can you see anything floating in the alcohol? That’s DNA!

 

The Science Bit:

The salt in the sports drink and the swishing motion you did with your mouth removed some cells from your cheeks. The pineapple juice and washing up liquid contain enzymes that can break down/digest cells. The salt helps to further break down the cells. Before you add the alcohol, the DNA is dissolved in the mixture. As DNA is very light, it floats up into the alcohol and clumps together enabling you to see it.