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I. Purpose: The purpose of this activity is become familiar with lab procedures for extracting DNA, collect a DNA sample and observe the physical characteristics.

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Presentation on theme: "I. Purpose: The purpose of this activity is become familiar with lab procedures for extracting DNA, collect a DNA sample and observe the physical characteristics."— Presentation transcript:

1 I. Purpose: The purpose of this activity is become familiar with lab procedures for extracting DNA, collect a DNA sample and observe the physical characteristics of DNA.

2 Safety Precautions:  Do not eat or drink in the laboratory.  Wear Apron & Safety Goggles. Research  What is the purpose behind DNA?  What is DNA composed of?  What do you think DNA will look like?  Where is the DNA located? Background: The long, thick fibers of DNA store the information for the functioning of the chemistry of life. DNA is present in every cell of plants and animals. The DNA found in strawberry cells can be extracted using common, everyday materials. We will use an extraction buffer containing salt, to break up protein chains that bind around the nucleic acids, and dish soap to dissolve the lipid (fat) part of the strawberry cell wall and nuclear membrane. This extraction buffer will help provide us access to the DNA inside the cells.

3 Materials:  heavy duty ziploc bag  1 strawberry  10 mL DNA extraction buffer (soapy, salty water)  cheesecloth  funnel  50mL vial / test tube  glass rod, inoculating loop, or popsicle stick  20 mL ethanol Procedure: 1. Place strawberry in a Ziploc bag. 2. Smash/grind up the strawberry using your fist and fingers for 2 minutes. Careful not to break the bag!!

4 Procedure: 3. Add the provided 10mL of extraction buffer (salt and soap solution) to the bag. 4. Kneed/mush the strawberry in the bag again for 1 minute. 5. Assemble your filtration apparatus as shown to the below.

5 Procedure: 6. Pour the strawberry slurry into the filtration apparatus and let it drip directly into your test tube. 7. Slowly pour 20 ml of cold ethanol into the tube. OBSERVE 8. Dip the loop or glass rod into the tube where the strawberry extract and ethanol layers come into contact with each other. OBSERVE 9. Swirl the glass rod around to grab the DNA at the top of the ethanol and place inside the vial. Remove all the DNA that is in the tube.

6 Conclusion, Data and Analysis: DNA Extraction Table Amount Added or Obtained Initial ColorPurpose Buffer (soap-salt mixture) Strawberry Cold Alcohol DNA Sketch of test tube with contents:

7 Conclusion and Analysis: 1. It is important that you understand the steps in the extraction procedure and why each step was necessary. Each step in the procedure 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 C. Initial smashing and grinding of strawberry D. Addition of ethanol to filtered extract ___ Separate components of the cell ___ Break open the cells ___ Break up proteins and dissolve cell membranes

8 2. What did the DNA look like? Relate what you know about the chemical structure of DNA to what you observed today. 3. Explain what happened in the final step when you added ethanol to your strawberry extract. ( Hint: DNA is soluble in water, but not in ethanol) 4. A person cannot see a single cotton thread 100 feet away, but if you wound thousands of threads together into a rope, it would be visible much further away. Is this statement analogous to our DNA extraction? Explain. 5. Why is it important for scientists to be able to remove DNA from an organism? List two reasons. 6. Is there DNA in your food? ________ How do you know?

9 I. Purpose: The purpose of this activity is to understand all organisms are made of the same material. The only difference is that the genetic material is simply rearranged.

10 Safety Precautions:  Do not eat or drink in the laboratory. Background: Cells from the lining of your mouth come loose easily, so you will be able to collect cells containing your DNA by swishing a liquid around in your mouth. The cells from the lining of your mouth also come off whenever you chew food. How do you think your body replaces the cells that come off the lining of your mouth when you eat? To extract DNA from your cells, you will need to separate the DNA from the other types of biological molecules in your cells. You will be using the same basic steps that biologists use when they extract DNA (e.g. to clone DNA or to make a DNA fingerprint). You will follow these 3 easy steps to extract the DNA: D etergent e N zymes (meat tenderizer) A lcohol

11 Materials:  Sports Drink / Water  DNA extraction buffer (soapy, salty water)  Water 50 degrees C  50mL vial / test tube  glass rod, inoculating loop, or popsicle stick  Protease enzyme (meat tenderizer)  ethanol Procedure: 1. Obtain 3ml of sports drink or water 2. Begin chewing on the inside of your mouth (Do not cause bleeding) 3. Place sports drink / water in mouth & swish vigorously for 30 seconds

12 Procedure: 4. Spit back into tube. 5. Add 2ml of buffer to tube (record observations) 6. Invert 5 times (do not shake) 7. Add a small pinch of enzymes (meat tenderizer) 8. Invert 5 times (do not shake) 9. Add 5ml of ethanol to tube by leaning the tube at a 45º angle and dropping ethanol down the side. 10. Place cap on tube and allow it to sit undisturbed for 5 minutes. 11. Slowly invert tube 5 times to help the DNA which as begun to precipitate to aggregate.

13 Procedure: 12. Use wooden stick to obtain DNA and place inside small vial. Observations, Analysis, Data: 1. Which of the following do you think will contain DNA? Explain your reasoning. bananas __ concrete __ fossils __ meat __ metal __ spinach __ strawberries __ 2. Describe the function of DNA polymerase. Explain why each part of the name DNA polymerase (DNA, polymer, -ase) makes sense. 3. The detergent and meat tenderizer opened the cell and broke down the cell components so that the DNA could be obtained. What other components of the cell might be found in the sample in your capped tube?


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