Day 22 Extracting Cheek Cell DNA

Today, in Biology, we had an end of module mock exam. To take our minds off this, and probably to distract us, we did a practical involving DNA extraction. We had a choice of extracting DNA from a strawberry, or from our cheek cells. Unsurprisingly, everyone in the class except for two students chose to extract DNA from our cheeks.

We put a ready-made solution of washing up liquid, salt and water into a test tube, and used a clean cotton bud to swab the inside of our mouths. It felt a bit like I was attempting to brush my teeth with a cotton bud. We then dipped our cotton buds into the test tube so that what we had swabbed could mix with the solution. Ice cold ethanol was added carefully down the side of the test tube, and a layer formed on the top, since alcohol doesn’t really mix with water. We waited a few minutes, and saw our precipitated DNA strands suspended in the layer. The practical was so fun, and we got to keep our DNA precipitates in small glass vials, with added ethanol to preserve it.


The wispy white bits near the bottom of the vial are my DNA 🙂


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