Thursday, January 10, 2008

DNA Lab at Home

This is great! We got a DNA kit for Christmas, but you can do this on your own.

I do think the kit is worth getting. There are 15 other experiments including one where you are genetically engineering bacteria to glow under UV light. That would be hard to do without a kit! Also, the kit has very good, kid friendly, full color explanations. The kit says 8+, Mxyl, Klenda and Zorg are very into it, Leena comes and goes.)

Here's how to extract DNA from fruit.

You'll need:
  • alcohol (rubbing is fine, ethyl works too) Put it in the freezer right away, it takes a while to chill.
  • fruit: banana, kiwi, strawberry, or onion. (Yeah, I know onion isn't a fruit... but it's got such huge cells you can see them with a good magnifying glass!)
  • laundry detergent
  • hot and cold water
  • ice cubes
  • thermometer
  • plastic measuring cup
  • funnel/ cups
  • coffee filter
  • 2 large bowls (that the measuring cup will fit it)
  • knife/cutting board/plate
  • fork and spoon or coffee stirrer
  • measuring tablespoon
  1. Cut half of your fruit (maybe use a whole strawberry) into small pieces and then mash them with a fork. The idea is break it up as much as possible. With an onion you could use a blender. Put this into the measuring cup.
  2. Add 1/2 cup of warm water and a tablespoon of laundry detergent to the mix and stir it.
  3. Put the measuring cup into one of the bowls and fill the outer bowl with very warm (125 degree F) water. You can use a mix of boiling water and tap water to get the right temperature. This is called a water bath. Keep it here for 12 minutes, adding hot water and stirring every now and then to keep it warm.
  4. While you wait, put ice cubes and cold water in the other bowl so that when 12 minutes are up you can put the measuring cup in the cold bowl. Let it chill maybe 5 minutes, stirring occasionally.
  5. Drain this goop through your coffee filter (placed in a funnel set in a cup is the easiest).
  6. When you get about a tablespoon of filtered liquid, that's enough (but you can collect more a do this several times). Take one tablespoon of the liquid and add one tablespoon of ice cold alcohol (this won't work if it's not ice cold) and a pinch of salt.
  7. Swirl to mix. It will suddenly turn goopy and clumpy as the DNA comes out of solution or "precipitates". Put the cup on ice for 10 minutes or so to get as much DNA out as you can (you can even stick it into the freezer overnight).
  8. Pull the DNA out with a spoon or fork, or just dump it onto a plate and mess with it.
  9. Eat the other half of the fruit! Did you ever think of how much DNA you eat?

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