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

1.1.One person-Obtain a One person-Obtain a beaker with detergent beaker with detergent solution and larger solution and larger beaker with alcohol.beaker with alcohol.

2.2.Slowly pour the detergentSlowly pour the detergent in you test tube just to coat coat the bottom of the tube.the bottom of the tube.

2. Obtain a cup of salt water.Obtain a cup of salt water.Salt water

3. Swish the salt water in your Swish the salt water in your

mouth for no less than 30mouth for no less than 30 seconds,seconds, then return your “cheek water” to your cup.

Remember to rub Remember to rub or chew on the or chew on the inside surface of inside surface of your cheeks to help your cheeks to help dislodge more dislodge more cells!cells!

4. Slowly pour enough “cheek . Slowly pour enough “cheek water” to make the test tube water” to make the test tube half full.half full.

5. Put the stopper on the test 5. Put the stopper on the test tube.tube.

Saliva

+salt

water

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

7. Let it sit for ten minutes.

No Bubbles? Great! Remove the cap and keep the test tube upright

from this point on!

Ellen

8. Tilt test tube slightly. Gently . Tilt test tube slightly. Gently pour alcohol along the side of pour alcohol along the side of the tube until almost full.the tube until almost full.

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

10. Let sit for 5 minutes. Use 10. Let sit for 5 minutes. Use stirring rod later to pull it stirring rod later to pull it out.out.

10. Wash cups and test tubes 10. Wash cups and test tubes out with soap. out with soap.

11. Return cups up front.11. Return cups up front.

Did everyone’s DNA look the

same?

Why did some people have more Why did some people have more DNA?DNA?

Why did some people have more Why did some people have more DNA?DNA?

What would have happened if you had been chewing gum?

QuestionsQuestions• 1. Are you looking at a single strand of DNA? Yes or no, explain 1. Are you looking at a single strand of DNA? Yes or no, explain

youryour• answer.answer.• 2. What was the purpose of the alcohol? 2. What was the purpose of the alcohol? • 3. What can be the benefits of extracting human DNA? Give at 3. What can be the benefits of extracting human DNA? Give at

leastleast• two.two.• 4. If you did not get a good result in this lab, what do you think 4. If you did not get a good result in this lab, what do you think

you did wrong? (If you were successful, do you think there was you did wrong? (If you were successful, do you think there was anything you could have done to improve your results?)anything you could have done to improve your results?)

• 5. Write a paragraph either agreeing with or arguing against the5. Write a paragraph either agreeing with or arguing against the• necessity of genetic engineering in plants or animals. (Hint: necessity of genetic engineering in plants or animals. (Hint:

SupportSupport• your point of view)your point of view)

Experiment w/different

concentrations of Gatorade/detergen

t

Try different swishing methods

Try using warm water to bathe the

test tube until it is

55°C

What other organisms can you

extract DNA from?