I’ve mentioned before that I just started my junior year of online classes at Florida Tech. It has been a great influence on Chase to see me writing essays and reading all the time. It also gives us a lot to talk about. A few months ago I took my biology class and for a lab assignment I had to extract the DNA from strawberries. I like to show Chase what I’m reading and share my graded assignments with him so having a hands on project that I could actually work on with him was pretty awesome. I’ve seen this experiment used in school labs from 7th to 11th grade so if you’ve got a tween or teen that’s interested in science this is a fun experiment that you can do together at home. Supplies:
- 1/2 cup of strawberries
- 1/8 tsp. non-iodized salt
- 1 cup cold water
- 2 tbsp. Liquid dish detergent
- Splash of pineapple juice
- At least 1/2 cup of very cold 91% isopropyl alcohol
- Coffee filter (I used a paper towel)
- Test tube or small glass
- Coffee stirrer
First, combine the strawberries, salt and cold water. This should have gone in a blender for 20 seconds, but I don’t have one so we used a 2 cup food chopper. They aren’t really made for liquid so it was pretty messy, but it got the job done and gave us a good laugh. Next, add the liquid dish detergent to the strained liquid and stir it gently, then, let it sit for five minutes. After doing everything above, we were left with 1/2 cup of liquid, but you may have more or less. Pour 1/3 of the liquid into the small glass jar (test tube would be easier to work with but I didn’t have one) and add just a splash of the pineapple juice to act as an enzyme.
Next, add the very cold 91% isopropyl alcohol to the mixture. (We kept the bottle of alcohol in the freezer for thirty minutes prior to beginning the experiment.) Slowly pour the alcohol down the side of the jar, being careful not to mix the liquids. You want to create a layer of alcohol on top of the strawberry liquid that is approximately an equal amount. The stringy, white DNA should begin to precipitate almost immediately.
After only five minutes we were able to use a wooden coffee stirrer to collect all the DNA that you see in the picture to the left. We had a lot of fun doing the experiment together and Chase thought that it was cool that he was helping me with my homework. Leave me a comment and let me know how it went if you try it with your kids. If you blog about it leave the link in the comment.