DNA is a complex molecule that contains the information necessary to build and maintain an organism, and all living things have DNA...including fruit! Learn how to extract DNA from fruit using this kitchen-friendly process, led by the COD BioTechnology Club.
Materials List
These are the materials you will need to follow along with this activity.
- Goggles for eye protection
- Measuring cup
- Measuring spoons
- Rubbing alcohol
- ½ tsp salt
- ⅓ cup water
- 1 TBSP Dawn dishwashing detergent or comparable brand (shampoo works too!)
- Glass or small bowl
- Cheesecloth or coffee filter
- Funnel
- Tall drinking glass or beaker
- ½ of a banana -or- 3 fresh or thawed strawberries minus the green tops (strawberries preferred)
- Test tube or small glass jar (baby food or spice jars work)
- Long toothpicks or skewer sticks
Safety Considerations
Eye protection must be worn for this activity. This activity should be done with adult supervision.
Procedure
- Place the container of rubbing alcohol in the freezer before starting the exercise. The alcohol must be cold.
- Put on your goggles
- To make the extraction liquid, mix the salt, water, and Dawn detergent in a glass or small bowl. Set the mixture aside.
- Line the funnel with the cheesecloth, and place the tube of the funnel into the beaker or tall glass.
- Put the banana or strawberries in the plastic bag and push out all the extra air. Tightly seal the bag.
- Squeeze and mash the strawberry mixture for 2 minutes. A blender works as well.
- Add 3 tablespoons of the extraction liquid (salt, water and detergent) from step 2 to the mashed fruit in the bag. Push out air and reseal the bag.
- Squeeze the fruit mixture with your fingers for 1 minute or more.
- 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.
- Discard the cheesecloth and the fruit 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. You will see the DNA begin to separate between the 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 from the nucleus of the fruit cells!