DNA for Dinner Lesson 3: DNA for DInner

1. Select 2 small kiwis, 6 strawberries or a small tomato - soft fruits work better.
2. Remove leaves, stems, skin (from kiwi and tomato) and chop coarsely.

3. Put in blender and blend to achieve "pumpkin soup-like" consistency. Add water if necessary. It is okay to be slightly chunky; don't overblend.

4. Add blended fruit to 8 oz. plastic cup to ~1/3 of cup's volume.

5. Add 1 teaspoon baking soda - it will fizz, especially with acidic fruits.

6. Stir several minutes until fizzing stops.

7. Add equal volume extraction mixture; stir for several minutes.

Extraction mixture
(can be scaled for smaller volumes):

In 1-quart container add:
- 4 tablespoons dishwashing liquid (e.g., Palmolive)
- 3 teaspoons iodized salt
- Add water to 1 quart

8. Put single layer coffee filter in strainer; filter mixture into glass. Discard pulp in strainer.

9. Add 1/2 teaspoon (2 milliliters) of this mixture to small transparent glass or plastic tube, using "eye dropper".

10. Using "eye dropper", gently layer 1 teaspoon (4 milliliters) of cold isopropanol down side of tube to form layer on top of mixture. Try not to mix layers.

11. DNA will appear at interface between alcohol and DNA mixture.

12. Unfold a paper clip leaving one end bent into a "U". Carefully twirl it at interface of two layers to capture DNA, which appears as a "snotty glob" on the clip.

Understand What's Happening

Each of the steps in this procedure is important to isolating DNA. Ask participants to speculate about what happened during each step of the procedure.

What do you think happened when you mashed the fruit in the blender?
Hint to leader: It breaks the tissue into smaller pieces and even breaks some of the cells open, allowing contents of the nucleus to spill out in long strands. But be careful; if you overblend the fruit, the nuclei will break open and the long DNA strands will be torn into small pieces.

What effect do you think the detergent had when you added it to strained fruit mixture?
Hint for leader: Detergent is added to "dissolve" the oily membranes that surround the cell, just like detergent is used to get hamburger grease off of a picnic plate!

What happened when salt was added to the mixture?
Hint for leader: Salt causes proteins and starch to come out of solution.

Explain what affect you think adding alcohol had on the DNA in the solution?
Hint for leader: After breaking the membrane and precipitating the proteins and starch, alcohol will cause the invisible DNA to come out of solution and form a white or yellowish, snotty-looking layer between the alcohol on top and the fruit solution on the bottom.

Remind participants that even though they isolated DNA from only one or two fruits, DNA is in all living things and therefore in meat, milk, eggs, yogurt, bread and cereals.



		Dessert There’s DNA in My Strawberry (Tomato, Kiwi)? 1. Select 2 small kiwis, 6 strawberries or a small tomato - soft fruits work better. 2. Remove leaves, stems, skin (from kiwi and tomato) and chop coarsely. 3. Put in blender and blend to achieve "pumpkin soup-like" consistency. Add water if necessary. It is okay to be slightly chunky; don't overblend. 4. Add blended fruit to 8 oz. plastic cup to ~1/3 of cup's volume. 5. Add 1 teaspoon baking soda - it will fizz, especially with acidic fruits. 6. Stir several minutes until fizzing stops. 7. Add equal volume extraction mixture; stir for several minutes. Extraction mixture (can be scaled for smaller volumes): In 1-quart container add: - 4 tablespoons dishwashing liquid (e.g., Palmolive) - 3 teaspoons iodized salt - Add water to 1 quart 8. Put single layer coffee filter in strainer; filter mixture into glass. Discard pulp in strainer. 9. Add 1/2 teaspoon (2 milliliters) of this mixture to small transparent glass or plastic tube, using "eye dropper". 10. Using "eye dropper", gently layer 1 teaspoon (4 milliliters) of cold isopropanol down side of tube to form layer on top of mixture. Try not to mix layers. 11. DNA will appear at interface between alcohol and DNA mixture. 12. Unfold a paper clip leaving one end bent into a "U". Carefully twirl it at interface of two layers to capture DNA, which appears as a "snotty glob" on the clip. Understand What's Happening Each of the steps in this procedure is important to isolating DNA. Ask participants to speculate about what happened during each step of the procedure. What do you think happened when you mashed the fruit in the blender? Hint to leader: It breaks the tissue into smaller pieces and even breaks some of the cells open, allowing contents of the nucleus to spill out in long strands. But be careful; if you overblend the fruit, the nuclei will break open and the long DNA strands will be torn into small pieces. What effect do you think the detergent had when you added it to strained fruit mixture? Hint for leader: Detergent is added to "dissolve" the oily membranes that surround the cell, just like detergent is used to get hamburger grease off of a picnic plate! What happened when salt was added to the mixture? Hint for leader: Salt causes proteins and starch to come out of solution. Explain what affect you think adding alcohol had on the DNA in the solution? Hint for leader: After breaking the membrane and precipitating the proteins and starch, alcohol will cause the invisible DNA to come out of solution and form a white or yellowish, snotty-looking layer between the alcohol on top and the fruit solution on the bottom. Remind participants that even though they isolated DNA from only one or two fruits, DNA is in all living things and therefore in meat, milk, eggs, yogurt, bread and cereals. Next: Stuffed, But Still Hungry for More?
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