BIOL107 Study Guide - Final Guide: Hersham And Walton Motors, Macromolecule, Missense Mutation
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BIO 111: DNA Extraction: Strawberry | DNA Spooling |
Background: Thelong, thick fibers of DNA store the information for the functioningof the chemistry of life. DNA is present in every cell of plantsand animals. The DNA found in strawberry cells can be extractedusing common, everyday materials. We will use an extraction buffercontaining salt, to break up protein chains that bind around thenucleic acids, and dish soap to dissolve the lipid (fat) part ofthe strawberry cell wall and nuclear membrane. This extractionbuffer will help provide us access to the DNA inside the cells.
Pre-labquestions:
What do you think the DNA will look like?
Where is DNA found?
Materials:
Heavy duty ziplocbag 10 mL DNA extraction buffer (soapy, salty water)
1strawberry glass rod, inoculating loop, or Popsicle stick
Cheeseclothfunnel 20 ml ethanol
50mL vial / test tube
Procedure:
1. Place one strawberry in aZiploc bag.
2. Smash/grind up thestrawberry using your fist and fingers for 2 minutes. Carefulnot to break the bag!!
3. Add the provided 10mL ofextraction buffer (salt and soap solution) to the bag.
4. Kneed/mush the strawberryin the bag again for 1 minute.
5. Assemble your filtrationapparatus as shown to the right.
6. Pour the strawberryslurry into the filtration apparatus and let it drip directly intoyour test tube.
7. Slowly pour cold ethanolinto the tube. OBSERVE
8. Dip the loop or glass rodinto the tube where the strawberry extract and ethanol layers comeinto contact with each other. OBSERVE
Conclusions and Analysis
It is important that you understand the steps in the extractionprocedure and why each step was necessary. Each step in theprocedure aided in isolating the DNA from other cellular materials.Match the procedure with its function:
PROCEDURE | FUNCTION |
A. Filter strawberry slurry through cheesecloth | ___ To precipitate DNA from solution |
B. Mush strawberry with salty/soapy solution | ___ Separate components of the cell |
C. Initial smashing and grinding of strawberry | ___ Break open the cells |
D. Addition of ethanol to filtered extract | ___ Break up proteins and dissolvecell membranes |
2. What didthe DNA look like? Relate what you know about the chemicalstructure of DNA to what you observed today.
Explain what happened in the final step when you added ethanolto your strawberry extract.
(Hint: DNA is soluble in water, but not in ethanol)
A person cannot see a single cotton thread 100 feet away, but ifyou wound thousands of threads together into a rope, it would bevisible much further away. Is this statement analogous to our DNAextraction? Explain.
Why is it important for scientists to be able to remove DNA froman organism? List two reasons.
Is there DNA in your food? How do you know?
