Waiter, there’s DNA in my dinner!

GMO Shortens Life Span by Michael. This shirt design was submitted to Atrium in the No GMO t-shirt design challenge.

Threadless recently hosted* a t-shirt contest for Jeffery Smith‘s Institute for Responsible Technology: the No GMO t-shirt design challenge (see Karl’s post Vote for talking, not fighting for more details). One of the shirts really struck me: GMO Shortens Life Span by Michael. The artist proposes an equation:

plants + DNA  = death

This slogan really makes me wonder – does the artist know that plants have DNA? Does he know that his own cells are teeming with DNA? That without DNA, life wouldn’t exist? Do most people know that DNA is essential for life? What would the average person say if told that they eat about 100 thousand miles of DNA in the average meal?

If this is the level of understanding, or rather, misunderstanding, that persons have, can we ever expect to have useful discourse on the subject of biotechnology or even biology itself? This worries me greatly. Just in case anyone out there reading this is concerned that DNA is dangerous, I’d like to provide a simple recipe that anyone can use to see and touch DNA for themselves.

As shown in the picture below, DNA is tightly packed in each cell. It’s wrapped around proteins called histones, then coiled into the familiar X chromosome shape. The amount of DNA per cell depends on the species, but each cell has about 9 feet of DNA in it. Since each meal contains tens of millions of cells, you eat about 7 to 10 miles of DNA at each meal!

Cells to DNA. Image from Michigan State University.

There are a lot of DNA extraction recipes out there, but there are a few essential steps. The DNA must be freed from the cell membrane and the membrane of the nucleus. Then, the DNA needs to be separated from the membrane bits, proteins, and other cellular parts. Finally, the DNA needs to be precipitated, or brought out of solution by becoming a solid instead of being dissolved in the solution.

Supplies:

  • Source of DNA. Fruit, especially banana or strawberries, works great because they have a lot of DNA per cell. Onions have a lot of DNA per cell too, but make for a much less pleasant smelling DNA extraction than berries or bananas.
  • Detergent, such as shampoo or dish soap. Clear detergent is better so dye doesn’t cover up the action.
  • Coffee filter to remove proteins, cell membrane parts, and other cellular gunk from your DNA solution.
  • Table salt to precipitate proteins and carbohydrates.
  • Ethanol to precipitate the DNA. Rubbing alcohol is ethanol, preferably 95%.
  • A plastic sandwich baggie.
  • 3 cups.
  • A plastic teaspoon.
  • A test tube or narrow glass like a shot glass.
  • Toothpick.
Recipe:
  1. Pour some rubbing alcohol into one of the cups and put it into the freezer.
  2. Prepare the fruit.
    • If using a banana, peel the banana. Set aside of eat half of it and put the other half into a plastic baggie.
    • If using strawberries, cut up about 5 medium strawberries into fourths. Put the pieces into a plastic baggie.
  3. Seal the baggie and use your hands to mash up the fruit. Set the baggie aside.
  4. Add 1 spoon of shampoo to one of the cups.
  5. Add 2 pinches of salt to the shampoo.
  6. Add 1/8 of a cup of water to the salt and shampoo.
  7. Stir until the salt and shampoo are dissolved. Stir slowly so the shampoo doesn’t foam up.
  8. Add about 3 spoons of fruit mash from the baggie to the salt and shampoo mixture.
  9. Stir the fruit solution with the plastic spoon for about 5 minutes, mashing any chunks of fruit against the wall of the cup.
  10. Place the coffee filter over the second cup, making sure the filter doesn’t touch the bottom of the cup.
  11. Pour the fruit solution through the filter. Wait for a few minutes to allow the liquid to flow through the filter.
  12. Slowly pour about 1/4 of the the filtrate (filtered solution in the second cup) into the cold alcohol so that the alcohol makes up about 3/4 of the final solution.
  13. Let the alcohol solution sit undisturbed for about 5 minutes. You should see the solution separate into two layers.
  14. While holding onto one end of the toothpick, put the other end in the top layer of the solution with the tip just in the interface between the two solutions, and gently twirl the toothpick. You should see clear strands that looks a little like mucous sticking to the toothpick. This – believe it or not – is DNA!
  15. If you don’t see anything, take the toothpick out and put the alcohol and DNA solution in the freezer for a few minutes. The cold temperature will help the DNA to precipitate. Then, with a fresh toothpick, try pulling out the DNA again.

    Stringy clumps of DNA in the alcohol layer of the solution. Image from the University of Utah.

Safety note: if you are tempted to taste the DNA, just remember that there is shampoo and rubbing alcohol in there and that these things are generally not good to eat! DNA itself, though, is perfectly safe – we eat it in every meal.  Really want to eat DNA? Check out these instructions for building an edible model.

*Just in case you were wondering, the contests aren’t vetted by Threadless, they are run by a separate site, Atrium. This was important for me, because I rather like Threadless, but I prefer to avoid patronizing companies whose publicized ethical stance I disagree with.

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