According to https://www.livescience.com/37252-dna-science-experiment.html when people think of DNA they usually visualize the elegant “twisted ladder” shape seen in everything from advertising logos to Biology textbooks. This visual is actually a kind of artist’s conception. It is a kind of scientific model, useful in helping us understand how DNA functions, but in reality impossible to see.
The structure of a molecule is far too small to be seen with even the most powerful of microscopes. Rosalind Franklin used the process of X-ray crystallography to make an image of the DNA molecule that was used by Watson and Crick to build that first model; but X-ray crystallography is a bit complex for most students to do at home.
Still, some of you might want to do something a bit more dramatic than building a DNA model out of toothpicks and gumdrops. You might not be able to actually see little A,C,T and G pieces, or even a single DNA strand, but did you know that you can use some common kitchen ingredients to extract DNA from your own cells.
Biology teacher, Ms Charmaine Drury, from Glenwood High School in Durban, walked the boys through the steps of DNA testing.
What You Need:
- Small paper cups (You want the smallest sized cups.)
- 1 bottle of colourless sports drink (You can also use a strong salt water solution, but “Lemon Ice” flavoured Gatorade tastes better — and you can use the leftovers for refreshments after the lab!)
- Liquid dish soap (You want to use the lightest colour or colourless brand you can find)
- A few drops of pineapple juice (You could also try using a quarter-teaspoon of meat tenderizer dissolved in a half-cup of water)
- 1 wood skewer (You want the kind that looks like a very long toothpick. Look in the baking aisle at the grocery store — many people use them to test cakes for doneness.)
- Alcohol (You can use regular rubbing alcohol, but if you can find 91-percent isopropyl alcohol at the drugstore get that. The closer to 100-percent alcohol you use, the better this will work.)
- Narrow container with a lid (You can use a test tube with a stopper if you have one. You could also use a small jar like you buy spices in. Make sure it is clean and dry.)
What to Do:
- 24 hours before you start, put the alcohol in the kitchen freezer. Don’t worry, it won’t freeze, but it should be ice cold before you do your experiment.
- Get a sports drink that is light colour or colourless.
Credit: DenisNataShutterstock. When you are ready, take a good mouthful of sports drink and vigorously swish it around in your mouth like mouth wash. Keep going for at least 2 minutes. This takes some stamina — it’s harder than it sounds, to swish for that long! It also helps if you scrape the insides of your cheeks a little with your teeth. No blood, please; we are after the DNA from your cheek cells, not your blood type!
- Spit the sports drink and cheek cell solution into a small paper cup, then pour it into your test tube or spice jar until it is about one-third full.
- Add liquid dish soap until your container is about half full. Put the lid on and mix the contents by rocking the container and turning it upside down several times. Be gentle, your goal is to mix the contents but to avoid causing bubbles from the soap.
- Add a few drops of pineapple juice or meat tenderizer solution. Repeat the gentle mixing.
- Gently add alcohol to the solution.
Credit: Genetic Science Learning CenterNow it’s time to get that icy cold alcohol out of the freezer. Take the lid off of your cheek cell solution and tilt the container in one hand. Use your other hand to very gently trickle a small amount of alcohol down the inside of the jar so that the alcohol forms a layer floating on top of the cell solution. Return the container to its upright position and set it aside for 1 minute.
- After a minute, look carefully at the place where the alcohol makes a layer floating on top of the cheek cell solution. You should see a band of white gooey material suspended between the liquid layers. Gently put the skewer down into the container so that the tip touches this material. Carefully twirl the skewer in one direction only; if you are lucky the stuff will wind around the skewer so that you can lift it out through the alcohol layer to look more closely.
- Behold your own DNA!