Strawberry DNA Isolation Lab

Objective Students will isolate DNA from a strawberry by performing an at-home lab experiment, photograph their results, and formalize their experience by writing a lab report. Background Information Before beginning the experiment, review chapters 23 and 24 of the course textbook, and watch the video provided on the course website showing the extraction of strawberry DNA (an example of the experiment that you will be completing here). Assignment Instructions 1. Follow the instructions below to extract DNA from a strawberry. Read through the instructions completely before starting the experiment. Materials two seal-able quart-size plastic bags (Ziploc™ type) one strawberry with the leaves detached (You can also use frozen strawberries, bananas, or split peas if fresh strawberries are out of season.) one coffee filter dish soap salt tap water 2 oz (1/4 cup) freezer-cold rubbing alcohol one coffee stirrer or toothpick Procedure a. Place the strawberry into one of the seal-able plastic bags. Once in the bag and sealed, squeeze and squish the strawberry through the bag for two minutes. Be careful not to rupture the bag. b. Put a small squirt of dish soap and small amount of salt (amounts do not need to be exact) into 4 oz (1/2 cup) of water. Mix the soap and salt in the water without forming a lot of bubbles. c. Add the soapy, salty solution into the seal-able bag with the strawberry. Seal the bag and squeeze/squish for two more minutes. d. Place the coffee filter into the second seal-able bag. Pour the strawberry mixture through the filter into the second bag (you may need a lab assistant for this part). Do your best to not allow it to leak. Not all of the contents from the first bag need to be filtered into the second bag. e. Layer the freezer-cold rubbing alcohol over the filtered mixture in the second bag, by allowing it to drip down the inside of the bag. Write down what you observe to happen once the alcohol is added. f. Spool out the white, stringy precipitant that forms in the bag with the toothpick or coffee stirrer – this is the strawberry DNA. g. Take a photo of the extracted DNA, which you will submit along with your lab report for this assignment. 2. Write a lab report which contains the following sections, presented in this order. Label each section of the report clearly in your write-up. Title Page – Come up with a title that specifically and accurately represents what the report is about. Center the title, your name, and the date on the title page. Abstract – write a brief and concise summary (100-150 word paragraph) of the experiment’s objectives, methods, results, and conclusions. NOTE: this section comes first, but should be completed LAST, since it is a summary your work. Introduction – Provide some background (about a 200 word paragraph) on DNA and its applications in the modern world. Discuss what DNA is, its role in living organisms, and some applications of DNA in criminology, medicine, etc., as discussed in chapter 24. Materials and Methods – This section should include all information necessary to repeat the experiment (materials needed (including amounts) and steps of the experiment procedure), written in narrative in form. In describing the methods (or procedure), include the following: For each of the following steps in the experiment procedure, Explain, in 2-3 sentences, the specific reason that the step was necessary for the extraction of the strawberry DNA. Cite any sources used in researching the reasons. - Initial mashing/squishing of the strawberries - Adding the soap and salt solution and continued mashing - Straining the strawberry mixture through the coffee filter - Adding the freezer-cold rubbing alcohol Results – A discussion (150-200 word paragraph) of the observations made during the experiment, in narrative form. In this section, explain what happened in the final step when you added the rubbing alcohol to your strawberry extract. The white, stringy material that precipitated out was the strawberry DNA. Relate what you know about the chemical structure of DNA to what you observed. Discussion – Your interpretation (150-200 word paragraph) of the experiment and results. Describe your experience while completing the steps of the experiment. What parts were difficult to complete? Did you have to repeat the experiment for any reason? Did you expect, or were you surprised, by the results? 3. Submit your completed lab report AND photo of the extracted DNA to the designated digital drop box on the course website. The report is worth 40 points and the photo is worth 10 points.