Nothing says Mother’s Day science more than DNA, right? Why not take that fruit salad you serve to mom for Mother’s Day brunch and do a little science and see DNA. You can pull the long molecules out of all kinds of fruit. And while you won’t see the actual ladder-twisty molecule up close, these molecules are so, so, so long that you can actually see the strands!You don’t have to be a geneticist. You don’t need a microscope. It’s easy, fun, and all you need are some household materials.
What you need
- Zip-lock bag
- Small jar or glass
- Water (1/4 cup)
- Dish soap (2 teaspoons)
- Salt (1/4 tsp)
- Coffee filter
- Tall thin Glass
- Isopropyl alcohol (chilled)
What you do
- Cut a kiwi in half and squeeze the insides into a Zip-Lock baggie.
- Seal the bag and squish it until it’s mush.
- Place the water, salt and soap in a small jar or glass and stir gently. This is your dismantling solution.
- Pour the dismantling solution into the baggie with the kiwi and zip it shut.
- Mix the contents well.
- Place a coffee filter over the tall thin glass.
- Pour the contents from the baggie into the filter and let it drip. This separates all the solids.
- Add about an inch of chilled isopropyl alcohol to the solution by pouring it onto a spoon that you’ve lowered into the glass. (This helps to keep it from getting jumbled. The alcohol should float on top.
- Can you see how there is a separation of white “stuff” atop the rest of the solution? That’s the DNA of the kiwi
What’s going on?
The long thick fibers you see in the extraction solution are strands of kiwi DNA. DNA is present in every cell of all plants and animals and determines the genetics of the individual organisms.
DNA comes packed into tiny pouches called nuclei. These are small organelles in every cell. They are surrounded by a tough membrane. The cell itself is surrounded by a tough membrane. Mashing up the fruit in a plastic baggie will not break through the membranes. That’s where the “dismantling” solution comes in. Each ingredient in the solution does a job. The soap helps to dissolve the fat that makes up cell membranes. The salt breaks up protein chains that hold nucleic acids together, releasing the DNA strands. Finally, DNA floats in isopropyl alcohol, especially when the alcohol is ice cold.
DNA is everywhere! It’s the blueprint of every living thing. Try it with other fruits. Strawberries work well, bananas and blackberries, too.