ONION DNA EXTRACTION

MATERIALS: FOR ONE CLASS OF 30

• One yellow onion
• 100 ml of buffer mixture (1.5 g noniodized salt, 10 ml of liquid dishwasher detergent, 90 ml distilled water)--chilled
• 50 ml of 6% solution of meat tenderizer (3 g meat tenderizer + 50ml distilled water). Generic brand tenderizer works better than Adolph's.
• 150 ml of ICE COLD 95% ethanol (put in freezer ahead of time)
• 30 test tubes
• 30 Pasteur pipets or glass rods
• blender
• funnel
• coffee filter (generic) or cheese cloth

PROCEDURE:

Slurry prep (Keep chilled if possible):

1. Cut onion into wedges and place in blender
2. Add 100 ml of chilled buffer/detergent solution
3. Frappe' mixture until well blended (approx. 1 minute)
4. Filter mixture with funnel and coffee filter into breaker that is on ice.
5. Distribute approximately 4 ml into each test tube for students.

STUDENT PROCEDURE:

1. Obtain test tube with onion filtrate.
2. Add approximately 2 ml of meat tenderizer solution. Note the appearance of the filtrate. Mix slightly with pipet.
3. Tilt the tube and slowly add up to an equal volume of cold ethanol down the side of the tube. You should see a distinct layer of clear ethanol over the colored filtrate layer.
4. Gently swirl a Pasteur pipet at the interface of the two layers. You should see white, glean type material begin to aggregate at the surface of the pipet. That material is DNA!

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