Did you know that you can see DNA without using a microscope? Most people know that DNA (or deoxyribonucleic acid, if you want to be technical) is the heritable material, which means it’s passed down from parents to children in all living things. DNA contains instructions to make proteins, which make each of us who we are. It took scientists a long time to learn that DNA was responsible for all of this, and even longer to learn what it looks like. And while we might not be able to recreate Rosalind Franklin’s X-Ray crystallography images that helped uncover DNA’s double helix structure, with just a few household items, we can see DNA with our bare eyes. That’s what we did at the Midtown Farmers Market on June 25th.
We did this by mashing up strawberries and adding a solution of water, dish soap, and salt. This solution breaks down the cell membranes, to make it easier to access the DNA of strawberries. After filtering out the chunks of strawberry, we are left with just a liquid that contains the DNA—but we couldn’t see it yet. To separate the DNA from the rest of the solution, we added cold rubbing alcohol. DNA can mix with water because both water and DNA are polar. That’s a fancy way of saying they both have charges, kind of like how magnets have a positive and negative end. But the rubbing alcohol is nonpolar, meaning there’s no charge. Because of these different charges, the rubbing alcohol can surround the DNA so that it’s no longer mixed into the water solution. Once we’ve added the rubbing alcohol, we can see white stringy swirls in the solution—that’s the DNA that was inside the strawberry!
If you want to try out this fun experiment at home, you can check out the instructions here. Happy experimenting!