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Ohio 4-H Youth Development

Ohio State University Extension

CFAES

Genetic Science – Extracting DNA

Join our 4-H teen as he steps into the world of genetics.

What are we learning about today?

All living things have DNA, your cells, your dog, strawberries, everything. DNA is hidden in your cells and can't be seen by the naked eye. But scientists have developed a way to pull DNA out of cells, and you can try it out yourself!

What do you need?

  • 3 strawberries
  • Rubbing alcohol that you've chilled in a freezer
  • Salt
  • Water
  • Dishwashing liquid
  • Resealable plastic bag
  • Small glass jar
  • Tall drinking glass
  • Funnel 
  • Cheesecloth
  • Bamboo skewer or toothpick
  • Measuring spoons and cup

Try it yourself.

  1. Mix your extraction liquid.
    • To do this, combine:
      • 1/2 teaspoon salt
      • 1/3 cup water
      • 1 tablespoon dishwashing liquid
  2. Prep the strawberries.
    • Remove the green stems
    • Put the strawberries in a resealable plastic bag, push out air, and seal it twice.
    • Squeeze and mash them (smash with your fingers) for about 2 minutes. You want them pretty well crushed. 
  3. Combine it together.
    • After the strawberries are mashed, pour 3 tablespoons of your extraction mixture into the bag with the strawberries. Remove extra air and reseal.
    • Gently squeeze the mixture for another minute. The detergent helps to break open cell membranes (so DNA is released), and the salt helps DNA molecules clump together so they are easier to pull out. 
  4. Start pouring.
    • First, set a funnel lined with cheesecloth over a tall glass. 
    • Pour your strawberry + extraction mixture into the funnel slowly. Let the liquid drip through, leaving behind pulp. 
    • When the dripping is done, pour the filtered liquid (now pretty clear) into a small jar. Fill it about 1/4 full. 
    • Tilt the jar and very slowly pour the cold rubbing alcohol down the side so it forms a layer above the strawberry liquid. 
      • Important: don't let the rubbing alcohol and strawberry liquid mix.
  5. Pull out the DNA.
    • Dip a bamboo skewer (or a toothpick) where the two layers meet, and gently twist it. You should see the DNA wrap around it.

Open and print the supply sheet for yourself!

Want to learn more?