Tuesday, June 16, 2015

Strawberry DNA Extraction; A Kid-Friendly Experiment

I was going to title this Hip Hip Hooray; It's DNA!  to let you know that this is fun and not intimidating.  If you're looking for a simple, enjoyable and interesting science experiment to do with the kids--this is it!  It's hands-on and safe for kids to do with adult supervision.  We don't usually sit around extracting genetic information from our food, but the boys are pretty interested in the human body right now so it was the perfect one to do.  It takes about 15 minutes to extract and observe DNA from the cells of a strawberry.  Strawberries are a great fruit to use because their cells have an abundance of DNA.


I used Steve Spangler's Science website and you can follow the steps here.  DNA (deoxyribonucleic acid) is the genetic information that is contained in every cell of living things; plant or animal.  It's the shape of a twisted ladder or double helix.  It is very small but when you follow these steps, you can see mass amounts of these strands.

1. Add 10 mL of dish soap to 90 mL of water (dish soap helps to dissolved the cell membranes to get the DNA out of the cells).


2.  Add 1/4 tsp of salt (salt helps to release the DNA strands).


3. Put a strawberry in a Ziploc bag. You don't need to remove the stem.


4. Pour your water, dish soap and salt solution into the Ziploc bag.


5.  Smash the strawberry.  Break it apart until there are no large pieces yet.  Obviously this is the best part.



6.  Use a filter so remove the large parts of the strawberry (you don't have to do this part).


7.  Observe. Don't drink it.  They thought it looked just like a strawberry milkshake.  We may have over-pulverized it as there were a lot of soap bubbles.


8.  Pour into a smaller clear container.   If you have a lot of soap bubbles, do not fear.  They will disappear in the last step.


9. Add 10 mL of rubbing alcohol (isopropyl alcohol) that you have chilled in the freezer.  We added a touch more.  DNA is not soluble (does not dissolve) in it so you can see the white strands in the top layer where the rubbing alcohol is. 


10.  Try to pull out some of the DNA floating in the top layer.  In the lab we use a glass rod but tweezers work just fine!



This is great for ages 5 and up.  The boys asked questions like "If I ate this, would I turn into a strawberry?" and " Is this in us?" and "We eat their DNA?"   If you do this experiment, let me know how it goes!  You can always pin it here and come back to it!

Love,
Louise

4 comments:

  1. This is so cool! What a fun thing to do!

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    1. I used to do it in Biology 12 or Science 10...totally works for younger kids, too!

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  2. Just pinned this to my homeschool science board! Thanks Louise!

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