/homemade_items

You know, extracting DNA at home is one of those classic lab experiments that feel like magic but are just pure, basic chemistry. The strawberry is the best candidate for this because it has an absurd amount of DNA. They are octaploid, which basically means they have eight copies of each chromosome while we only have two. So, the amount of genetic material you can actually see at the end is way bigger than if you tried it with a banana or any other fruit. To set up your home lab and make sure everything goes smoothly, you will need to gather the following items: * Three very ripe strawberries * Liquid rubbing alcohol, 70% or 90% (left in the freezer for two or three hours) * Dish soap (preferably clear) * Table salt * Warm water (around 60 degrees Celsius / 140 degrees Fahrenheit) * A plastic bag with a zipper seal (like a Ziploc) * A paper coffee filter * A clean, clear glass cup * A toothpick or a wooden skewer The first thing to do is prepare the mixture that will break open the strawberry cells. In a glass cup, mix about 150 ml of warm water with a tablespoon of dish soap and a flat teaspoon of salt. The secret here is to stir very, very gently. If you start whipping it and create a bunch of soapy bubbles, it will ruin things later when you try to filter and see the DNA. The idea behind the water being warm—about the temperature of a hot bath—is to help speed up the process without destroying the DNA. Next, you pull the green leaves off the strawberries and throw them into the plastic bag. Seal it tightly while squeezing the air out, and start smashing them with your hands. Keep crushing until it turns into a completely smooth puree. This part is the mechanical breakdown of the cell walls. Then, open the bag and pour about four tablespoons of that water and soap mixture inside. Seal it up again, give it a gentle mix with your fingers for about two minutes so the soap touches everything, and let it sit quiet for about ten minutes. During this wait, the soap is basically dissolving the fat membranes of the cells and releasing the DNA. It is the exact same principle as washing a greasy pan after dinner. The salt does its part here too; it helps the DNA molecules clump together instead of repelling each other. Once that waiting time is up, comes the part that requires a little bit of patience, which is filtering. Place a regular paper coffee filter over a clean cup and pour the strawberry mush inside. Do not try to squeeze the filter with your hands to make it go faster; if you squeeze the paper, pieces of pulp will pass through and your liquid will turn cloudy and messy. Just let it drip on its own until you have about two fingers of a very clear, red liquid at the bottom of the cup. Now comes the moment of truth. Grab that alcohol from the freezer and tilt the cup with the strawberry juice slightly. Pour the alcohol very slowly down the side of the glass so it doesn't mix into the red juice, but instead creates a clear layer floating right on top of it. You will need to add roughly double the amount of alcohol compared to the volume of juice you have left. Almost immediately, you will start to see some whitish, gooey strings rising from the red liquid into the clear alcohol layer. It looks a bit like a wet spiderweb. That is the DNA clumping together because it cannot dissolve in freezing cold alcohol. Then you just take a toothpick or a skewer, place it right at the boundary where the two liquids meet, and spin it gently. The DNA will stick to the stick just like cotton candy, and you can pull it out in one piece. It is pretty cool to see up close. To help you visualize the process in practice, you can watch the [National Human Genome Research Institute Strawberry DNA Extraction Tutorial](https://www.youtube.com/watch?v=zMw44VDqf2s). This video, produced by researchers at the US National Institutes of Health, visually shows the exact step-by-step process of mixing the ingredients and what that whitish cloud of DNA should look like at the end of the experiment.