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DNA Extraction Lab Please do not write on this sheet Let’s make DNA Visible Stem cells contain all the genes needed to give rise to any of the body’s 200 different tissue types, including skin, bone, and heart cells. Where are gene stored? Along a double- stranded molecule called DNA, which can be found inside every cell’s nucleus. Without DNA, stem cells would lack their incredible morphing powers. Normally, DNA is microscopic because it is encased inside cells, but with the right tools, you can make it visible. Purpose: In this experiment, you will extract real DNA from the different foods. Materials Food sources Dropper liquid detergent Stirring rod 14 mL rubbing alcohol (90% ethanol) Filter paper 20mL hot tap water (50-60 degrees Celsius) Mortar and Pestle 50mL test tube Graduated cylinder Procedure 1. Place small portion of food in mortar. Grind using pestle for about 1 minute (until food is all mushy) 2. Place food source in test tube 3. Add 20mL of soapy water 4. Mix gently (about 5 seconds) every one minute for 5 minutes. (Try not to create any foam, but if you do – use a dropper to remove it.) 5. Tilt the test tube at a 45 degree angle and slowly and gently pour 15mL of ethanol down the side of the test tube so that it forms a separate layer on top of the solution. DO NOT mix the solutions together. DNA separates from the food at the water-alcohol boundary. If alcohol mixes with water, the solution will become too diluted and the DNA will not precipitate (form). 6. Let the test tube sit for a few minutes. White, stringy, DNA (looks like mucus) will begin to appear at the water-alcohol boundary. After 5-10 minutes, the DNA will float to the top of the alcohol layer. Analysis Questions Answer each question in a complete sentence on a separate sheet of paper. 1. Would you be able to extract DNA from animal cells using these methods? 2. Why do we add detergent to the test tube? (Hint: Soap contains enzymes.) 3. What does “precipitate” mean? 4. What is left in the bottom of the test tube after the DNA has been extracted? 5. What does the alcohol do? Why does the DNA rise to the top after adding alcohol? 6. What part of the cell does the DNA come from?
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