Student Objectives 2. To prepare a solution containing their DNA. 1. Precipitate their DNA to make it visible. 3. Compare the DNA samples from others in the class to see that at this level, DNA looks the same no matter where it comes from.

Getting Started DNA is found in the cells of all living things Students will be able to see their own DNA protein strands The solutions work together to release the DNA strands from the cell membranes Alcohol is added to the solution to precipitate the DNA

What do you need? Distilled/Bottled Water 3 oz. Plastic Cup Small test tube w/cap or plastic tube w/lid from a florist 1 Tsp. dish soap/shampoo mixed with 3 Tsp. water 1 Tsp. Gatorade® Very Cold Ethyl Alcohol (91% or greater, keep on ice) Eye Droppers or disposable pipettes Paper Towels for clean-up J

Let's see some DNA! Obtain a Dixie cup and write your name on it if you like Giese J

2. Fill your cup up half way with water. (already done!) Giese J

3. Swish the water in your mouth for no less than 1 minute then return your “cheek water” to your cup. Remember to rub your tongue on the inside surface of your cheeks to help dislodge more cells!

J 4. Slowly pour enough “cheek water” to make the test tube 1/3 full. Giese J

5. Add detergent solution into your test tube and cap the tube. Your test tube should be ½ full now.

6. Gently rock (NOT SHAKE!) the test tube back and forth to mix the contents, so that bubbles do not form.

No Bubbles? Great! Remove the cap and keep the test tube upright from this point on!

8. Add about 5 mL of ice cold ethyl alcohol. Your test tube should be 3/4 full now.

9. Observe the interface for the precipitation of the DNA 9. Observe the interface for the precipitation of the DNA. Small bubbles with white strings attached will slowly make their way to the top of the alcohol. This is DNA!

10. Pour contents of test tube back into plastic cup and dispose of the materials as directed. “Super Intern” Erin Fay J

Interface Precipitate Key Terms Interface Precipitate

Discussion ? ? ? ? Did everyone’s DNA look the same? Why did some people have more DNA? ? What would have happened if you had been chewing gum? ?

Want some more Ideas? Try using warm water to bathe the test tube until it is 55°C What other organisms can you extract DNA from? Experiment w/different concentrations of Gatorade/detergent Try different swishing methods

References St. Louis Science Center UIUC – Hughes Biotechnology Education and Outreach Program