DNA Extraction


Objective

In this experiment, we'll be extracting DNA. 

Supplies

  • Raw food items (i.e. strawberries, onions, split peas, or bananas - strawberries work berry well)
  • Table Salt
  • Liquid Detergent (Sunlight brand or Pantene Pro-V clarifying shampoo)
  • Distilled Water
  • Plastic Bags
  • Test Tubes
  • Bleached Coffee Filters (White)
  • Blender
  • Toothpick or Chopsticks
  • Chilled Isopropanol/Ethanol (95%, 0ºC)
  • Small Airtight Bottle (optional)

Procedures

  • Prepare the Lysis Buffer:
    • For every 100 mL of lysis buffer:
      • Combine 90 mL distilled water with 10 mL detergent.
      • Add 1.25 ml of salt.
      • Stir carefully until thoroughly mixed, making sure no bubbles form.
  • Prepare the Sample:
    • Place the food item in a plastic bag and pulverize until liquid, using a blender beforehand if necessary.
    • Add 10 mL of the lysis buffer to the bag and seal. 
    • Mix well, and continue to mash the bag for another 2 minutes. Add more lysis buffer if the mixture is too thick.
  • DNA Extraction
    • Use the coffee filter to strain the mixture into a beaker. Transfer the resulting liquid into a test tube.
    • Carefully and slowly float a layer of cold alcohol on top of the liquid. Use an equal or greater portion of alcohol to food mixture.
    • After a few minutes, white clumps of DNA strands will accumulate at the top of the tube. Use a toothpick or chopstick to remove these clumps.
    • Store in a small airtight container if desired, submerging the DNA in alcohol to preserve it.

Take-away

What is DNA? How is DNA organized? nucleotides → genes → chromosomes → genome

What are some properties of DNA? Polar - charged phosphate