Can you pull DNA out of an onion using supplies from your kitchen? DNA is packed tightly inside every cell. A few common chemicals can break those cells open and make the DNA visible.
You chop an onion and soak the pieces in a solution of three key ingredients. Detergent breaks open cell membranes. Salt and EDTA protect the DNA. Hot water helps burst the cell walls. Meat tenderizer breaks down proteins that cling to the DNA. After filtering the liquid, you pour ice-cold ethanol down the side of a test tube.
A white, stringy mass rises to the surface. That mass is pure DNA. You spool it onto a glass rod and lift it out.
Hypothesis
The hypothesis is that the DNA can be separated from the other cell components.
Every onion cell holds a complete copy of the code that tells the plant how to grow. That code is tightly packed inside the cell, hidden behind membranes and wrapped in proteins. Detergent breaks open those membranes, and meat tenderizer removes the proteins. Cold ethanol then pulls the DNA out of solution as a white, stringy mass you can lift with a glass rod.
DNA extraction pulls DNA out of cells so scientists can study it. This experiment uses detergent, salt, and hot water to break open onion cells and release their contents. Once ice-cold ethanol is added, a white, stringy mass rises to the surface — pure, visible DNA.
Method & Materials
You will gather materials, chop onions into small pieces, measure out ingredients, line a funnel with a coffee filter, pour the mixture into the funnel, let the liquid filter through, add a meat tenderizer solution, add ice-cold ethanol, swirl gently, and observe the results.
You will need 200mL of distilled water, 2 onions, 1 pair of glasses, 2 bottles of ethanol, 10mL of dishwashing detergent, 1.5gm of table salt, 5mL of EDTA, 3gm of meat tenderizer, 1 cutting board, 1 kitchen knife, 3 coffee filters, 1 large funnel, 1 thermometer, 300mL of water at 60 degrees C, 100mL of ice, 2 beakers (250mL or bigger), 1 wooden spoon, 1 small test tube, 1 plastic transfer pipet, and 15mL of ice-cold ethanol.
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The results of the experiment showed that DNA could live separated from the other cell components. This stands out as an interesting observation, as it shows that DNA can survive on its own.
Why do this project?
This science project is interesting and unique because it shows that a lot of DNA can be taken out of the onion and we can see the DNA at the end, even though we cannot see it when it's inside the onion cell.
Also Consider
Experiment variations to consider include using strawberries instead of onion to extract DNA.
Full project details
Additional information and source material for this project are available below.
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
Did you know you can also take out the DNA from strawberries? In this video, two scientists from the National Institute of Health demonstrate this using household items. You can do this too!
