Chill the alcohol
Take one clear glass and pour ¼ cup of rubbing alcohol in it. Then place the glass in a freezer in order to chill it. You can also place the glass in a bowl of ice. Remember that you need to chill the alcohol in order to extract the DNA effectively.
Mash the strawberries
Take three strawberries and take their stems out with help of a knife. Then place these strawberries in a re-sealable or Ziploc bag and seal it. Now mash the strawberries which you can do with the help of your fingers or with a fork. This procedure will require few minutes.
Add shampoo or dish liquid into the salt mixture
Now take the second glass and add two large pinches of salt. Pour a cup of tap water and stir in order to dissolve the salt. Then you need to add two tablespoons of dish liquid or shampoo in the salt mixture and mix the ingredients by stirring it.
Add the soapy solution in the bag
After making the soapy solution, you need to pour five teaspoons of it in the Ziploc bag containing mashed strawberries. Now seal the bag again and mash with help of your fingers for almost a minute. This mixture opens the cells of strawberry and releases the DNA.
Stir the mixture
Get the third glass and place a coffee filter over it. Secure the filter with a rubber band and pour the mixture into the filter. This process will take around 10 minutes.
Add chilled alcohol in the mixture
After getting the filtered mixture, you need to add chilled alcohol in it. Wait for five minutes for the clumpy white substance or the DNA to be formed. Take a toothpick and examine it carefully.