DNA – the building blocks of our body – is a complex idea for kids. I had no idea, though, how truly simple it was to start the process of obtaining it.
In fact, it only takes a few simple supplies and mere minutes to remove the DNA from a strawberry. My science-loving scout and I tried out this DNA extraction experiment at Celebrate Science Indiana this weekend. We had learned about taking DNA out of plants at the Science Center in St. Louis last summer, but this activity truly made it manageable – and repeatable if we wanted to use this activity as part of our Detective badge.
How to Extract DNA from a Strawberry
What you need:
- measuring cup
- measuring spoons
- rubbing alcohol
- 1/2 teaspoon salt
- 1/3 cup water
- 1 tablespoon dishwashing detergent
- glass or small bowl
- tall drinking glass
- 3 strawberries (green tops removed)
- reclosable plastic sandwich bags
- test tube or small glass jar (like the kind spices come in)
- bamboo skewer or pipette
What to do:
- Chill the rubbing alcohol in the freezer. (You’ll need it later.)
- Mix the salt, water, and detergent in a glass or small bowl. Set the mixture aside. This is your extraction liquid.
- Line the funnel with the cheesecloth, and put the funnel’s tube into the glass.
- Put the strawberries in the plastic bag and push out all the extra air. Seal it tightly.
- With your fingers, squeeze and smash the strawberry mixture for 2 minutes.
- Add 3 tablespoons of the extraction liquid you made in Step 2 to the strawberries in the bag. Push out all the extra air and reseal the bag.
- Squeeze the strawberry mixture with your fingers for 1 minute.
- Pour the strawberry mixture from the bag into the funnel. Let it drip into the glass until there is no liquid left in the funnel.
- Throw away the cheesecloth and the strawberry pulp inside. Pour the contents of the glass into the test tube or small glass jar so it is 1/4 full.
- Tilt the test tube or jar and very slowly pour the cold rubbing alcohol down the side. The alcohol should form a layer on top of the strawberry liquid. (Don’t let the alcohol and strawberry liquid mix. The DNA collects between the two layers!)
- Dip the bamboo skewer into the test tube where the alcohol and strawberry layers meet. Pull up the skewer. The whitish, stringy stuff is DNA containing strawberry genes!