DNA Extraction from a Strawberry © Sanford PROMISE 2015 #SanfordResearch Facebook: Sanford Research

DNA Extraction from Strawberry Lab Journal Overview Deoxyribonucleic Acid, the genetic code, is a microscopic macromolecule that is a necessary component to all living things. The code, made up of nucleic acids, is what distinguishes each living thing from another. Your DNA is unique to you and only you, unless you have an identical twin – you share the same genetic code. Your DNA is more like that of another human than any other organism, and more like any other animal than to plants, fungi, protozoa, or bacteria. Objective Through the activities below, one can extract DNA from fruits and even your own cheek cells with most of the supplies available at the grocery store. You will be able to see a precipitate/clump of DNA extracted from the nucleus of the cells. Extraction From Strawberries A regular favorite of DNA extraction, most fruit is easy to homogenize and contains a large amount of DNA. Strawberries are octoploid which means they have 8 copies of each chromosome (humans have 2 copies). In fact, strawberries even contain pectinases and cellulases that help to break down the cell walls (remember that plants have both a cell wall and a cell membrane). To get started, review the ingredients needed and how they work. Shampoo or dishwasher soap: Dissolves the lipid bilayer, cell membrane (much like it does the oils in your hair/on your dishes. Salt - Sodium Chloride (NaCl): Removes the proteins bound to the DNA. Also, helps keep the proteins dissolved in the water so they do not precipitate with the DNA in the last step. Ethanol or Isopropyl Alcohol: Precipitates the DNA. When the DNA comes out of solution it tends to come together, which makes it visible. Protocol: 1.Remove the sepals from strawberries (if applicable). 2.Place 1-3 strawberries into a zipper-style bag and seal shut. 3.Squish for 3-5 minutes to completely squash the fruit. 4.Add 3mL of 0.9% NaCl What is NaCl? Where do you have 0.9% NaCl in your body? 5.Add 3mL of DNA Lysis What is in DNA Lysis? Why is that needed? 6.Filter the homogenate and collect ~3mL of flow through. 7.Select an alcohol to precipitate the DNA. Which did you choose? Why? 8.Add 3mL of alcohol to a clear tube. 9.Gently add the fruit filtrate to the alcohol tube, noticing that the filtrate passes through the alcohol to the bottom of the tube forming a separate layer from the alcohol. 10.Wait for ~1 minute – you should see a precipitate start to form at the interface between the two liquids – precipitated DNA! Was your extraction successful? Can you think about why or why not? 11.Use a glass stir rod (or folded paperclip, coffee stirrer, or transfer pipet) to wrap some of the DNA around. 12.The DNA you’ve extracted from the cells of the fruit is safe to handle, view under a microscope or analyze with additional tests. Cool DNA Resources DNA Interactive: DNA Learning Center: Learn. Genetics: