DNA Extraction from Kiwifruit- Teacher Handout

Introduction

DNA is present in the cells of all living organisms. This procedure is designed to extract DNA from kiwi in sufficient quantity to be seen and spooled. This activity is ideal for students to work in pairs, but each student will have a tube of DNA at the end.

Materials

• knife for cutting kiwi
• one small ziplock bag per group of students
• jar or beaker that fits strainer or funnel
• strainer or funnel
• cheese cloth (or a #6 coffee filter)
• ice water bath (a large mixing bowl works well)
• water
• clear-colored shampoo, such as Suave Daily Clarifying Shampoo
• kiwifruit, half a kiwi per group of students
• table salt, either iodized or non-iodized
• 1 large test tube (holds 20 ml) per group, preferably with a cap
• 1 small test tube (holds 10 ml) for each student, preferably with a cap
• cold 95% ethanol (grain alcohol)

Protocol

1. Set up an ice water bath.

2. Each group will use half a kiwi and 20 ml of the following shampoo solution:
For one liter of the shampoo solution, mix 100 ml of shampoo and 15 g of table salt. Add water to make a final volume of 1 liter. Dissolve the salt y stirring slowly to avoid foaming. Measure 20 ml of solution for each group of students.

3. Peel the kiwi, cut them into about 12 pieces.

Directions for each group:

4. Get 6 pieces of kiwi and put them in a ziplock bag.

5. Add 20 ml of shampoo solution to the ziplock bag. Make sure the bag is closed with out much extra air. What do you think the shampoo solution does to the kiwi?

6. Mush the kiwi thouroughly but carefully so the bag doesn't break, for about 5 minutes. What does mushing the kiwi do?

7. Cool the kiwi mixture in the ice bath for a minute. Then mush the kiwi more. Cool, then mush. Repeat this several times. Why do we cool the mixture?

8. Filter the mixture through cheesecloth. All the groups can combine their mixtures at this point, to filter together. What is being filtered out? What is going through the filter?

9. Dispense approximately 3 ml of kiwi solution into each test tube, one for each student.

10. Being careful not to shake the tubes, add approximately 2 ml of cold 95% ethanol to each tube. What do you think the ethanol does? Why do we want it cold?

11. Take a look at your tube. What do you see in the top portion of the liquid?

Adapted from UNiv. Arizona