FruitDNAExtractionLab DNA Extraction Lab shampoo

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					                                  DNA Extraction Lab


DNA is present in the cells of all living organisms. This procedure is designed to
extract DNA from strawberry or other fresh fruit 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.

Some questions to get you thinking about today's lab: answer these
questions in your lab book.

One way to purify a molecule is to get rid of everything but that molecule. If we
want to isolate DNA from bacteria, what do we have to get rid of?
What materials would you use to do that?
What type of DNA are we purifying?
What can we do with the DNA once we've purified it?


      knife for cutting fruit
      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
      two strawberries or other pieces of fruit per group
      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)
      rubber band

1. Set up an ice water bath.
2. Each group will use two strawberries and 20 ml of the following shampoo
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 by stirring
slowly to avoid foaming. Measure 20 ml of solution for each group of students.
3. Cut the fruit into several small pieces.
Directions for each group:
4. Put the pieces 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
6. Mush the strawberry thoroughly but carefully so the bag doesn't break, for
about 5 minutes. What does mushing the strawberry do?
7. Cool the mixture in the ice bath for a minute. Then mush more. Cool, then
mush. Repeat this several times. Why do we cool the mixture?
8. Filter the mixture through filter.. What is being filtered out? What is going
through the filter?
9. Dispense approximately 3 ml of fruit solution into each test tube, one for each
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
11. Take a look at your tube. What do you see in the top portion of the liquid?
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Show your isolated DNA to the teacher, part of your
grade on this lab is the result, good pure DNA in large

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