Today, I had a fantastic visit with the girls at Girls Inc. in Lynn, where our outreach fellow, Sarah, runs the Beach Sister Program. The program is dedicated to teaching girls about marine biology and environmental issues, but it’s also about introducing them to scientists and showing them that they can do science too. I brought some photos of my fieldwork with corals and then we talked about DNA and did a strawberry DNA extraction using household products. In all honesty, I had no idea how excited they would be about DNA and doing the extraction. It was awesome!
I mean, DNA is cool – as we all know from CSI – but the concept of DNA can be a bit elusive. It’s in our cells and the cells of all living things, but it can be hard to visualize, and this simple project can make it more tangible. Even when you work with DNA in a molecular biology lab, you may only see DNA as a little white dot at the bottom of a tube, or as a band fluorescing with ethidium bromide on a gel, or see the evidence of it as a list of As, Cs, Gs and Ts in a computer file. DNA is small by our standards, but there is actually quite a lot of it in our bodies and in the living things we see all around us, and yes, it’s in the things we eat.
Extracting DNA from a fruit, like a banana, or some strawberries, is quite easy and can be done with common household ingredients (a list with links to protocols and demonstrations is at the bottom of this post). Strawberries are good because they are fun, colorful, AND octoploid (they have eight sets of chromosomes), which means they have lots of DNA. However, the girls could not come to a consensus on whether the strawberry/DNA extraction buffer mixture smelled ‘good’ or ‘gross’. If you want to get more personal, you can do a very similar procedure to extract your own DNA from epithelial cells in your mouth… Although, that little clump of DNA has nothing on the snotty gob of DNA you will get from the strawberries. But, that’s up to you… why not try them both?
Tomorrow I am heading to Norfolk, VA for Benthics (aka, the Benthic Ecology Meeting), and I hope the audience for my talk there is as excited as my audience today. Since my talk is on Saturday, close to the end of the conference when everyone will be worn out from two and a half days of powerpoint presentations, maybe I should stock up on some household DNA extraction materials, just in case.
All you need is:
- Your fruit of choice
- A ziplock bag, a clear cup, and a measuring spoon & cup
- Dish soap, or hand soap, or shampoo
- Table salt
- A strainer, or a coffee filter, or cheese cloth, or a (paper)towel
- Isopropanol, or ethanol (these will work best when chilled)
- A popsicle stick or stirrer
Protocols & Demonstrations for the Strawberry DNA Extraction: