Sophomores Extract DNA from Bananas

Jenna Paul and Dacy Buerkle with the DNA they extracted.

By Ashley Sander

The sophomore students in Mrs. Schumacher’s biology class have recently been learning about macromolecules in cells and DNA. They have focused on the four main macromolecules, which are nucleic acids, proteins, lipids, and carbohydrates. For an educational and hands-on lab, they were able to extract the DNA from a banana.

The first step in this process was to place half of a banana into a bag and mash it. Next, the students took a half a cup of hot water and dissolved some salt into it. After that, they added the salt-water mixture and dish soap to their bag, after which they gently combined it with the banana. Then, they strained the contents of their bags through a filter into a graduated cylinder. Finally, they added isopropyl alcohol on top of the mixture, making sure that it did not combine with the liquid below. The isopropyl alcohol formed a layer on which the DNA floated. The students were even able to pick up the clumps of DNA with tongue depressors. Students learned that the lab worked because the salt drew the water from the cells, and the soap broke down the outer layers of the cell. This released the DNA, which was able to float up into the alcohol because it had a lower density than the rest of the mixture. Overall, this lab was a very fun and educational experience for the class.


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