Name: _________________________ _________________________ _________________________ _________________________ _________________________ Date: ______________ Teacher: Tr. Oli Grade/Section: ___________________ Gen. Bio 2 | DNA Extraction from Cheek Cells Introduction: DNA is a nucleic acid, made of carbon, hydrogen, oxygen, nitrogen, and phosphorous. DNA can be considered the hereditary “code of life” because it possesses the information that determines an organism’s characteristic and is transmitted from one generation to the next. You receive half of your genes from your mother and half from your father. Day to day, DNA’s job is to direct the functioning within the cells of your body. Objectives: At the end of this experiment, you should be able to: 1. Know that DNA is found in the nucleus of cells 2. Learn how to extract DNA from cells and describe the purpose of the key steps of cell lysis, protein degradation and DNA precipitation; and, 3. Observe the appearance of human DNA Materials: Salt Liquid soap 70% + Isopropyl alcohol “cooled” ; 100 mL beaker to contain Distilled water Drinking or tap water Electronic balance (with filter paper or weighing boat) Paper cup/plastic cup Procedure: 1. Create an 8% sodium chloride solution by doing the following: Using a 100 mL graduated cylinder, measure 92 mL of distilled water. Place the water into a 250 mL beaker. Measure and place 8 grams of sodium chloride into the beaker with the distilled water. Stir the “saline solution” with a clean stirring rod until the salt is somewhat dissolved. 2. Have you and your partner(s) clean your mouth of any residual food items by rinsing your mouth with drinking water or using a drinking fountain prior to the next step. 3. Fill both you and your partner(s) paper cups with drinking water about 1/4 full. You and your partner(s) need to then swirl the drinking water in your mouths for 5 minutes; it would help greatly if you also firmly, yet gently scraped the inside of mouth (no blood) with your teeth to insure a high cell count and thus DNA. 4. Slowly relinquish the “mouthwash” solution back into a paper cup; then, relinquish “again”, (there will not be much saliva), but be forceful about it to insure a great cell count. Carefully pour the “mouthwash” solution, the entire contents, into a test tube and set aside for both you and your partner(s). If you have more solution than the test tube can hold, just fill it up ~ 3/4 full of “mouthwash” 5. Using the 25 mL graduated cylinder, measure 25 mL of distilled water. Place the distilled water into the other 250 mL beaker. Using the same graduated cylinder, measure and place 5 mL of liquid soap into the beaker with the distilled water. Gently stir the “soap solution” with a clean stirring rod until the solution is well mixed with few suds. 6. Using an eyedropper, place 1 dropper “full” of liquid soap solution from the beaker into both yours and your partner(s) test tubes containing the “mouthwash” solution and set aside. 7. Using an eyedropper, place 1 dropper “full” of the saline solution from the beaker into both yours and your partner(s) test tube containing the “mouthwash” and “soap” solution. 8. Cover the top of the test tubes with a lid and while holding your thumb on the lid, gently mix the contents by turning the test tubes upside down and right side up about 10 times slowly. 9. Using an eyedropper, place 5 dropper “fulls” of “cooled” 70-91%+ isopropyl alcohol into the test tubes containing the mouthwash, soap, and saline solution. Make sure to pour it at an angle down the side of the test tube. It is highly important that no sudden movements of the solution be performed during this time. 10. Place test tubes in a test tube rack and wait for a couple minutes for the DNA to appear and float toward the surface. Refer to the introduction section of this lab to establish an understanding about how the DNA materialized from solution, why the DNA is where it is in the test tube and what the appearance of the DNA should be in the test tube. In reality, you are looking at nucleic acid that contains a mixture of DNA and RNA. Post-Lab Questions: 1. Why does the DNA become visible once the alcohol is added? 2. Why is DNA referred to as your genetic fingerprint? 3. What do you think is the function of detergent? 4. What do you think is the function of alcohol?
