DNA Extraction Lab- A berry full of DNA!
Purpose: To extract DNA from the nucleus of a strawberry and physically see the massive amount of genetic material in a living object.
Background: In this lab you will break open strawberry cells, and separate DNA. Every strawberry contains eight copies of each of its chromosomes. (To compare you have two copies of each of your chromosomes). Ethanol is used to allow the DNA to precipitate out of solution and make it easy to harvest.
Procedure:
Materials
One Strawberry Funnel
One Ziplock Bag Test Tube
5 mL detergent solution Test Tub Rack
1 mL pipette 10 mL cold ethanol
Cheese Cloth inoculating loop
1. Place a strawberry in a ziplock bag. Press the air out of the bag and seal it.
2. Mash the bagged strawberry with your fist for two minutes.
3. Add 5 mL of detergent solution to the bag. Press air out and seal it.
4. Mash the bagged strawberry for 1 minute
5. Set up your filtration device as demonstrated by Miss H. (Place the cheese cloth in a funnel and place the funnel in the test tube. Use the test tube rack to hold the test tube.
6. Pour the liquid extract from the Ziploc bag into the cheese cloth and let it drip directly into the test tube. You may want to add a little water to your extract if it won’t filter.
7. When the test tube is 1/8th full, remove the funnel. Discard cheesecloth and Ziploc bag.
8. Slowly drizzle 10 mL of cold ethanol down the side of the test tube until it is half full. The ethanol should form a separate layer on top of the strawberry extract.
9. Dip an inoculating loop into the test tube where the ethanol and extract meet. Gently twirl the loop to collect a small portion of DNA. Observe the properties of DNA as it clumps together.
10. Dump all liquids down the sink, clean out test tube and return materials.
Data
Title______
Analysis and Conclusion:
What do you believe the purpose of the following steps was?
a. Mashing fruit to a slush
b. adding detergent solution
c. filtering strawberry extract
d. adding cold ethanol to extract.
How much DNA do you think a cherry would have compared to a strawberry? Why?
How do you think it is possible that this large amount of DNA fits in each cell? What does this suggest about the structure of DNA in cells?