Posted by: gillarbuthnott | February 1, 2013

Brian Cox’s DNA…

KONICA MINOLTA DIGITAL CAMERAToday I write wearing both my author and my biology teacher hats at a jaunty angle.

‘Ooh,’ someone said to me. ‘Did you see Brian Cox on Wonders of Life extracting his own DNA just by spitting into a test tube?’ Well, I hadn’t, so I hot footed it over to BBCiPlayer and watched. The Prof did indeed spit into a test tube, add a bit of washing up liquid and a sachet of salt, give it a shake, then pour on some vodka (I think it was vodka). Lo and behold, whitish strands of DNA appeared in the tube. All very impressive.

I’m very intrigued. I’ve been extracting DNA from various fruits and veg with school pupils and during author talks for years – the picture above is some strawberry DNA I extracted just this week. (It’s the white blobby stuff floating in the purple layer). The experiment does use only the chemicals that the prof used, but also involves heating and cooling, and much stronger alcohol. (If you’re interested, you can find instructions on the funscience website, or in my forthcoming book What Makes You You?) The reason I use fruit and veg is that this very simple procedure doesn’t – as far as I know – work for human DNA.

I do understand that a good experiment does not necessarily make for riveting television, so perhaps we weren’t shown everything, much like the phone ad that says ‘some sequences may have been shortened’. I tried the extraction myself as shown on the programme, and you certainly get a big whitish blob of stuff, which will contain some DNA, but, as I understand it, most of what you see will be mucus and protein.

I’d love to know if I’m wrong, so that my classes/audiences can get even more excited about DNA than they do at the moment. After all, who wants strawberry DNA if you can see your own? Can anyone out there enlighten me?


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