Tuesday, November 05, 2019

DNA extraction

We've moved on from human genetics (a bit) to discuss the life cycles of plants (since that's where our textbook went next). I decided that instead of planting seeds in different environments, we'd do some DNA extraction for one of our experiments (since we have acorns sprouting (or not sprouting) all over our yard currently and since my kids know the parable of the sower, this didn't seem like a very riveting experiment to do (What?! You mean the seed left on the empty lid didn't sprout even when left in the sunny window while the see that we put into the soil, which we made sure got plenty of sun and water did sprout?! Who would have thought?!); we do, however, have an oak tree growing in our kitchen window sill (and several sprouting all over the lawn, but none sprouting on our driveway; go figure))).

Like I said, this textbook sometimes feels a little juvenile for Miriam (and sometimes even for Benjamin). 

The DNA extraction, though, was right up our alley. I'd seen this idea pop up a few times over the years and decided to pull it out now since we were studying both DNA and plants and happened to have a few pumpkins on hand. 

Weirdly, while I could find several videos (like this one) telling how to extract the DNA, none of the videos discussed why anyone would ever need to extract DNA from something. Fortunately, a quick internet search gave me plenty of reasons why (genetic modification, crime scene samplings, cloning, and so forth) so we had plenty to discuss.

After pulverizing a bit of our pumpkin in the blender (with some water to make it nice and juicy), I scooped some into baggies for each of the kids to squish and added some dish soap and salt (our washing solution). Once their pumpkin puree was thoroughly mixed with the soap and salt, we ran it through a strainer and (since I couldn't find any cheese cloth) some paper towels. 

Here we are squishing our mixture into our strainer:

And here we are helping things along by using a a pestle: 

Here's Miriam dumping our refined pumpkin juice/soap mixture into our test tube:

Next we poured in some isopropyl alcohol and watched with acute fascination as all the soap bubbles disappeared and our mixture settled into three separate layers


They look bored out of their minds, but I assure you they were in fact absolutely fascinated. Rachel came home while we were in the middle of watching things settle and also became very interested in what we were doing. Here she is holding up the test tube so you can see the layers (the cloudy stuff in the middle is the DNA, the clear stuff is the isopropyl alcohol, and the orange stuff is pumpkin):

Now we were ready to clone our pumpkin!

Just kidding! We were actually ready to make dinner, so while discussing the ethics of cloning we cleaned up from our experiment, and put science aside for the day.

Oh, and we also made a little human DNA chain on the kitchen floor as well:

Zoë and Benjamin make up the D, Miriam and Alexander make up the N, and Rachel is doing her best to be an A

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