How to Extract DNA for a Science Project
DNA is an exciting topic and lots of fun to learn about in science class. The scientific name is deoxyribonucleic acid. This molecule is fragile, small and found within the nucleus of cells. The molecule is twisted into a helix and the two separate strands are held together by hydrogen bonds. DNA contains the instructions for the cells to function in very specific ways. Your DNA is what makes you who you are. You can extract DNA from your own cells to use for science projects and experiments.
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Things You'll Need
- Bottle of cold rubbing (isopropyl) alcohol
- Medium size bowl filled with Ice
- Tap water
- Salt
- Two 500 ml Erlenmeyer flasks or beakers
- Glass stirrer
- Graduated cylinder
- Liquid dish detergent
Instructions
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1
Refrigerate the bottle of isopropyl alcohol overnight. When you are ready to do the extraction, immerse the isopropyl alcohol bottle in the bowl with the ice. Set the bowl aside.
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2
Add 1 teaspoon of salt to 100 ml of tap water in one of your flasks or beakers. Stir the salt into the water until it dissolves. You will use the saltwater to collect your DNA. Set the flask aside.
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3
Measure 25 ml of tap water and 15 ml of liquid detergent in your graduated cylinder. Pour both items into a clean flask. This soapy solution is what you will use to hold your DNA sample until you are ready to extract it. Gently stir and set aside.
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4
Pour about half of the saltwater into a household glass or mug. Swirl the saltwater inside your mouth, then spit it into the flask containing the water and liquid detergent mixture.
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5
Release the DNA from the nuclei of your cheek cells by slowly and gently stirring the soapy mixture for three minutes. Now your mixture contains the released DNA but you cannot yet see it.
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Pour about half a bottle of the cold rubbing alcohol into the flask with your cheek cell mixture. You need to pour it, so that the mixture slowly flows in around the sides of the flask. Do not stir it this time. Let the mixture sit for at least five minutes, so that layers form. The top layer is your DNA.
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Gently and very slowly swirl the mixture using the glass stirrer. You will see what look like threads swirling around your stirrer. It may take a little while for this to happen, so keep slowly stirring if you do not see the threads right away. Gently lift your stirrer out of the mixture. Those sticky, thin threads are your DNA. The DNA is ready to use for your project.
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Tips & Warnings
Science experiments and procedures require patience. Do not rush through the steps. Once you get started, the DNA extraction process does not take very long. However, you will not get good results if you rush through the steps.
You can substitute freshly minced onions or other vegetables as the source of DNA.
Children should be supervised by adults when completing this process.
Keep these items out of the reach of small children and pets. Properly dispose of all items at the conclusion of the experiment.
Be sure that no items are ingested. In case of accidental ingestion, immediately contact your poison control center or emergency medical services.
