Education

DNA is in every living cell.  The photos to the right are individual plants cells that have been squashed and stained to reveal the chromosomes in the nucleus.  They are from an aquatic invasive weed called flowering rush (Butomus umbellatus).  The chromosomes are the dark purple "worm-like" things in the center of a cell.  These photos were taken at different depths in a cell so that the chromosomes can be followed to their ends in order to accurately count their number.

You can purify DNA with common ingredients in your house.


DNA from strawberries
Strawberries are great to use - they smell great and they have lots of DNA, but any fruit or vegetable also works.  The softer ones work the best.

Here is a video of how to isolate strawberry DNA:
http://www.youtube.com/watch?v=hOpu4iN5Bh4

You will need:
Strawberries (fresh or frozen)
Sealing baggie
Plastic cup (clear is best)
Lysis solution (below)
Coffee filter
Rubbing alcohol

Recipe for lysis solution:
2 tsp detergent (dish, shampoo, hand soap)
1/2 tsp salt
1/2 cup water


DNA from your cheek cells
You can get lots of DNA from your cheek cells.  Companies that trace your ancestry send you a kit to take a swab from your cheek.
  
You will need:
Clear screw cap tube that holds 1 tblsp (15 mL)
1/2 tsp water
1/2 tsp lysis solution (same as above for strawberries)
2 tsp rubbing alcohol

Scrape  your gums with your teeth vigorously for 30 seconds.  Put the 1/2 tsp water into your mouth and swish around, then spit it carefully into the 15 mL tube.

Add the 1/2 tsp lysis solution and gently invert a few times to mix.  Do not make bubbles!

Add the 2 tsp rubbing alcohol and replace the cap.  Let sit for a few minutes without mixing.  Do you see cloudiness in the upper alcohol layer?  This is DNA.  Invert gently.  You should see the white DNA clumps of precipitated DNA.

Brenda Grewell and Joy Futrell, University of California, Davis

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