DNA Extraction SCIENCE 10 LAB AND REPORT Hello Scientists! Today, you will be extracting the DNA from a strawberry. Here are the materials you will need: 15 mL of extraction liquid (salt, water, and dish soap) 10 mL of very cold rubbing alcohol Funnel Cheese cloth 25 mL graduated cylinder 1-2 strawberries Large sandwich-size Ziploc bag PPE 25 mL beaker (for extraction liquid) Before you get to work, answer the Pre-Lab questions on the following page! Procedure: 1. Gather the materials you need and make sure you are set with your PPE! Your teacher will provide you with the rubbing alcohol further along. 2. Put the strawberries in your plastic bag, pushing all of the air out before sealing it. 3. Once the bag is sealed, use your hands to mash the strawberries from outside of the bag for about 2 minutes, until you get a jam-like consistency. 4. Add your extraction liquid to the bag, seal the bag again, and mash the strawberries for another minute or so. 5. Fit your cheese cloth to the funnel, and fit your funnel over the graduated cylinder 6. Pour the mixture slowly through the cheese cloth until all of the liquid is in the cylinder. 7. Very slowly, pour the rubbing alcohol into the cylinder of strawberry liquid. Pour at an angle for optimal results - your teacher will show you how to do this! 8. Let rest for a few minutes as you take some observations. 9. As the DNA starts to appear, make some observations of it's appearance and any other things you noticed! You can also use a toothpick or pin to poke your DNA and see how it reacts. If you'd like to do this, ask your teacher for the materials! 10. Clean up your materials based off of your teachers instructions! Pre-Lab Questions & Predictions! Where does the DNA exist within the strawberry? Why do you think we have to mash the strawberry to access its DNA? What do you think the DNA will look like? Lab Questions & Observations! What did you observe when you poured the alcohol into the strawberry juice liquid? What did your DNA look like? Is it what you had predicted? Did it surprise you? Compare the amount of DNA you can see in your graduated cylinder to the amount in another classmates. Are they the same? Does someone have more DNA? Why do you think this might be? Post-lab Questions & Reflections! Is there anything about this lab that surprised you? If so, share it here! Do you think we got all of the DNA from inside the strawberries? Explain your answer. If we continued this experiment, what would you want to do next? How do you think scientists utilize this experiment within the real world? Why would we want to look at DNA? Think about the size of your strawberries before you mashed them. Teacher Notes Curricular Competencies addressed/How they will be assessed: Evaluate their methods and experimental conditions, including identifying sources of error or uncertainty, confounding variables, and possible alternative explanations and conclusions (assessed through the lab report, mainly the question: "Do you think we got all of the DNA from inside the strawberries?" This question is meant to encourage students to think about uncertainties/sources of error within their experiment) Transfer and apply learning to new situations (assessed through the lab report, mainly in questions about continuing the experiment, and how scientists may utilize these methods in the real world. These questions are meant to encourage students to extend their knowledge and apply it in different ways) Ensure that safety and ethical guidelines are followed in their investigations (assessed through observations throughout the lab; are they sticking to the safety rules? Behaving in a safe and responsible manner?) Use knowledge of scientific concepts to draw conclusions that are consistent with evidence (assessed through lab report, mainly the question about the amount of DNA retrieved from the strawberry compared to a classmates. This question is meant to encourage students to think about if larger strawberries have more DNA, and why that might be, i. e. larger strawberries may have more cells, so more DNA due to more cells) If students ask, the extraction liquid is made up of water, detergent, and salt! The detergent is used to disrupt the phospholipid bilayer of the cells, allowing the cells to burst open and letting us access all the stuff inside the cell! The salt is used to break up the proteins that are holding the DNA together, allowing us to access the DNA! Also, the alcohol is used to clump the DNA together as DNA doesn't like alcohol, so it clumps up together at the edge of the alcohol, allowing us to access it quickly. The alcohol needs to be kept very cold, so maybe prepare it while students are mashing up their strawberries. Everything is okay to go down the sink with a lot of water! The strawberry guts that get filtered out can go in the garbage. Lab Introduction: Distribution: students can complete this lab in their table groups, so as far as distribution I would like to set up materials around the room, and send the table groups to different stations to pick up their materials, before rotating to another station. I think the baskets would be a great tool to use for distribution! PPE: goggles must be worn from the distribution of materials until cleanup is finished! Safety: Most materials in this lab are generally quite harmless! If there is anyone with an allergy to strawberries, bananas can be used instead, and it can be performed in a separate room maybe! There is a possibility of spills and broken glass. If either of these occur, please let the teacher know and I will come help you clean it up! Don't ingest the rubbing alcohol. If it gets in your eyes, past your goggles, we will have to use the eyewash station for at least 20 minutes! If it gets on skin, rinse well with water. Clean up: All liquid waste can go down the drain with lots of water! Any solid wastes, like the strawberry guts, can go in the garbage. Glassware must be cleaned and returned to the proper stations! Clean up must be checked by your teacher before you can go!
