Every cell of every living thing holds a copy of DNA. DNA is the genetic material that determines what creature we are and our characteristics. In this lab, you will be able to extract the DNA of a strawberry! Strawberries are easy to extract DNA from because they are soft and and packed with DNA. The dish detergent will dissolve the cell membrane while the salt will break down the proteins to release the DNA strands. Then, the rubbing alcohol will capture the DNA molecule. You could try this experiment with other fruits
like kiwi and melons and compare how much DNA you extract from each fruit.
- rubbing alcohol
- 1/2 teaspoon salt
- 1/3 cup water
- 1 tablespoon Dawn dishwashing detergent
- glass or small bowl
- cheesecloth (or paper towel)
- tall drinking glass
- 3 strawberries (green tops removed)
- reclosable plastic sandwich bags
- test tube or small glass
jar (spice or baby food jar)
- bamboo skewer, straw, or cotton swab
- Chill the rubbing alcohol in the freezer, until needed.
- Mix the salt, water, and Dawn detergent in a glass or small bowl and set aside. This is your extraction liquid!
- Line the funnel with the cheesecloth or paper towel, 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 at least 2 minutes, try to get it as pulpy as possible.
- Add 3 tablespoons of the extraction liquid you made 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 or paper towel 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, straw, or cotton swab into the test tube where the alcohol and strawberry layers meet. Pull it upr. The whitish-clear, gooey stuff is DNA containing strawberry genes!