Observations and results
Were you able to see DNA in the small jar when you added the cold rubbing alcohol? Was the DNA mostly in the layer with the  alcohol and between the layers of alcohol and strawberry liquid?

When you added the salt and detergent mixture to the smashed strawberries, the detergent helped lyse (pop open) the strawberry cells, releasing the DNA into solution, whereas the salt helped create an environment where the different DNA strands could gather and clump, making it easier for you to see them. (When you added the salt and detergent mixture, you probably mostly just saw more bubbles form in the bag because of the detergent.) After you added the cold rubbing alcohol to the filtered strawberry liquid, the alcohol should have precipitated the DNA out of the liquid while the rest of the liquid remained in solution. You should have seen the white/clear gooey DNA strands in the alcohol layer as well as between the two layers. A single strand of DNA is extremely tiny, too tiny to see with the naked eye, but because the DNA clumped in this activity you were able to see just how much of it three strawberries have when all of their octoploid cells are combined! (“Octoploid” means they have eight genomes.)

More to explore
Do-It-Yourself Strawberry DNA, from the Tech Museum of Innovation, Stanford School of Medicine
About Genetics, from the Tech Museum of Innovation, Stanford School of Medicine
DNA Extraction Virtual Lab, from Learn Genetics, the University of Utah
Do-It-Yourself DNA, from Science Buddies

This activity brought to you in partnership with Science Buddies

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