DNA Extraction

We did a DNA Extraction from peas this past week.  The DNA looks remarkably like . . . snot.  That would be because both DNA and snot are made of similar proteins.  It’s a little weird though that the whole control center of your body’s cells resembles the nasty stuff on your tissue.


How To Extract DNA From Peas

  1. In a blender, mix ½ c. split peas, 1/8 t. salt and 1 cup of water.
  2. Blend for about 15 seconds. The blender has now separated the peas into their individual cells. If you like you can take a smear of the pea juice and look at it under your microscope.
  3. Pour the pea mixture through a strainer and into another container. (Save the liquid part, toss the solid.)
  4. Add 2 T. dishwashing liquid and stir. The dishwasher soap will dissolve the fatty lipids that make up the plasma membrane and the nuclear membrane, leaving the DNA free floating.
  5. Let sit for 10 minutes.
  6. Pour the mixture into three separate test tubes.
  7. Add ¼ t. meat tenderizer (found by the spices in the grocery store) to each test tube and stir gently. The meat tenderizer is an enzyme, a substance that causes chemical reactions to occur in a living thing, and will help unravel the strands of DNA.
  8. Now carefully tilt one test tube and slowly pour isopropyl or ethanol alcohol into the test tube until you have as much alcohol as pea juice.
  9. Look at the place where the alcohol and pea juice meet. There should be some white stringy stuff. The stringy stuff is DNA.


Additional Layers

  • You know how when you have a cold, you think, “If I blow my nose really well than all this nastiness in my nose will go away”  but then it doesn’t, the snot just keeps coming and coming.  How does your body do this?  Find out how cells make the stuff they make.
  • DNA is both simple and complex.  It’s only made with four different protein compounds.  The compounds are just arranged in different patterns and orders to make the whole code.  Tim observed that this is kind of like the binary code with which computers are programmed, only in the body it’s a quaternary code.  Pretty cool stuff.
  • Each strand of DNA is a single molecule; it’s one of the very few molecules you can see with the naked eye.
  • DNA stands for deoxyribonucleic acid . . . you will probably never need to know this in your real life.  But still, probably the only word you know that’s longer is supercalifragilisticexpialidocious, and that’s just nonsense.
  • This experiment is from Unit 2-6 of the Layers of Learning curriculum, which contains way more cool stuff like this.


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