Name:__________________________________        Hr:________        Date:______________ 

DNA Plant Cell Extraction

Purpose:

Students will see that DNA is contained within all cells. In order to see the DNA within the cell, the cells membranes must be broken down. Cell membranes can be broken down with a simple household solution. The large amounts of DNA within the cells’ nucleus will then clump together by also adding a household solution. Finally, we will add cold ethyl alcohol to precipitate the clumps of DNA so that it is visible.

Materials:

• 100 mL - Water (if you have deionized it is better, but works fine with tap water)
• 1 spoonful - raw wheat germ
• 1 squirt - liquid soap - lyses the cell walls
• 1/2  tsp. - meat tenderizer - breaks up the proteins surrounding the DNA
• 1 Tbsp. - baking soda - raises the pH to about 8.0
• Cold ethyl alcohol - (you can buy at your local pharmacy) - pulls out the DNA
• 100mL graduated cylinder plastic spoon
• Clear plastic cup (about 9 oz)
• Clear test tube
• 2 bulb pipettes 

Procedure:

1. Measure 100 mL of water and pour into a plastic cup.
2. Add one spoonful of raw wheat germ and stir continuously for about 2 minutes.
3. Add one squirt liquid soap continuing to stir for another 2 minutes.
4. After 2 minutes add 1/2 tsp of meat tenderizer continuing to stir for another 2 minutes.
5. Add 1 Tbsp. of baking soda continuing to stir for another 2-3 minutes.
6. After 3 minutes, the solution should start to thicken.
7. Set the cup aside allowing the solution to separate. You will see the wheat germ and protein fall to the bottom of the cup leaving two distinctive layers. The bottom one cloudy and full of debris. The top clear and a golden color.
8. Using pipette transfer the liquid (or top layer) to the test tube filling it approximately halfway.
   Make sure you are only placing the liquid, not the debris in the test tube.
9. It is very important not to shake, stir, or tip the test tube after this step.
10. Using a clean pipette add enough cold ethyl alcohol to fill the test to about 3/4 full.
11. Again, do not tip, shake, or stir the test tube, or you will not see the DNA.
12. The point where the two layers meet (the liquid and the alcohol), or the interface will start to bubble. If you watch these bubbles rise you will see white hair like strands attached. These strands are the DNA of the Wheat Germ you started with.

Questions:

1. What do the letters DNA stand for?

2. What is DNA made of?

3. What does DNA do for us? Why do we need it?

4. Where is DNA found within cells?

5. Can DNA be found in all cells? Explain.

6.  What did the soap solution do to your cells?

7. What did the salt solution help your DNA do?

8. What was the cold ethyl alcohol for?