Friday, May 21, 2010

Science Time: Extract Strawberry DNA

Yes, you read that correctly, extract DNA from a strawberry.  The best part is that you don't need anything fancy to do it, you probably have everything at home!  We did this at the Pacific Science Center on a "Meet a  Real Scientist Day."

2 Strawberries
small baggies
2 plastic cups
non-iodized salt
wooden stick (like a bamboo skewer, or Popsicle stick)
rubbing alcohol (cold)

To keep the strands of DNA intact throughout the isolation, you need to handle everything gently (after the smashing of the strawberry).  If you do this, you will be rewarded at the end with long. gooey strings of DNA.

1. Place on strawberry in a baggie, seal the baggie and squish the strawberry until it is the consistency of a smoothie (small chunks are OK)
2. Add an equal volume of water (just guess, it doesn't have to be exact).
3. Add 2 small squirts of shampoo and about a teaspoon of salt. Mix this up GENTLY by tilting the baggie back and forth (no more smushing)

4. Strain the mixture through 2 layers of cheesecloth into a plastic cup. Allow the liquid to drip through.  After most of the liquid has dripped through, you may gently squeeze the cheesecloth to get more liquid out.

It will look like this picture to the left, no solids left.

5.Add an equal volume of cold rubbing alcohol to the clear, pink liquid and gently swirl the cup.  You should see strings of clear DNA form and float to the top. Use the wooden stick to twirl the gooey DNA around and pick it up out of the liquid! This is DNA!

The text content of this experiment comes from a handout, "DNA: The Stuff of Life", The South Lake Union Group (, from the 2/24-3/3/03 issue of the US News and World Report - adapted from the Washington University Young Scientist Program.

Some great links about DNA for kids are:
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Kim @ seven thirty three said...

That is really cool!

Thanks for linking up with What are little boys made of?

Jamie said...