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Saturday Science: Wheat Germ DNA Extraction

Saturday Science: DNA Extraction from Wheat Germ

The DNA in raw wheat germ is enclosed in the nucleus of the cell.  To extract the DNA, we must first break open the cellulose cell wall by vigorously shaking a mixture of cells and warm water.  The warm water (between 55 and 60 degrees Celsius) will deactivate an enzyme in the cell that can break down DNA.  After the cell wall is broken down, our next barriers are the cell membrane and nuclear membrane.  The warm water will melt the membranes and soap can be added to dissolve the lipid layers.  Once the DNA is free in the mixture, it can be precipitated out by adding a layer of ethanol.  The DNA precipitates out because it is insoluble in ethanol and now the DNA can be spooled onto a wooden stick for collection.

Materials

  • 1 gram of raw wheat germ 
  • 20mL hot water
  • 1 mL dishwashing soap 
  • 10 mL running alcohol 
  • Vial 
  • Graduated cylinder 
  • Wooden stick 

Process 

  1. Measure 1 gram (1/2 teaspoon) of raw wheat germ into a vial.
  2. Measure 20 mL of hot water (55-60C) into a graduated cylinder.
  3. Pour the hot water into the vial of wheat germ.
  4. Shake vigorously for 3 minutes.
  5. Add 1 mL of dishwashing soap.
  6. Shake gently to minimize foam for 2 minutes.
  7. Remove foam.
  8. Gently add 10 mL of ice-cold ethanol or rubbing alcohol.  Add it slowly so that the alcohol floats in a layer on top of the wheat germ mixture.
  9. Where the alcohol and mixture meet, a white precipitate will form.  Collect the precipitate by spooling it onto a wooden stick.

The white precipitate contains the genomic DNA of wheat.  It may also contain some polysaccharide or protein.

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