Biology, Answering the Big Questions of Life/DNA lab

From Wikibooks, open books for an open world
Jump to navigation Jump to search
DNA condensation


Deoxyribonucleic acid is a very long molecule found in each cell of a living organism that holds the information about how to run the cell. In this lab, you will isolate DNA from strawberries and look at it.

PURPOSE To isolate and observe DNA.


  • Clean Strawberries (green tops removed)
  • Plastic Sandwich bags.
  • 95% Ethanol (cold)
  • Extraction Buffer
  • A glass rod
  • plastic pipet
  • glass test tubes
  • Test tube rack


1. Place a clean strawberry into one of the sandwich bags, and mash it using thumb and fingers until it is in small pieces.

2. Add 3 ml of the extraction buffer into the bag. Mash with strawberry and let sit flat on table for five minutes.

3. Transfer into a glass test tube. Let it sit upright in a test tube rack for five more minutes.

4. Place the glass stir rod in the test tube so that it touches one side of the tube just above the surface of the strawberry solution. Then slowly drizzle 3 ml of cold ethanol into the tube so that it makes a separate clear layer above the strawberry solution.

5. Let sit undisturbed for two minutes.

6. The clear strands of DNA will start to spool out into the ethanol. It will form a disturbance at the interface as the DNA precipitates out into the ethanol solution. It may look like white puffs. Lower the glass rod to almost touch the place where the color changes. Stir twice in small circles, then pull the glass rod out of the solution. You should see a mucus-like clear string attached to the glass rod. THIS IS THE DNA.

7. If you wish to save the DNA, use the pipet to suck out the white cloud of DNA and transfer it into another test tube for storage.