Strawberry DNA Extraction Lab (Grade 9)

In this lab, we utilized a buffer (shampoo/dish detergent, salt, distilled water) to break through the cell walls of strawberry cells and isopropyl alcohol to precipitate out the DNA from the strawberry mash.

We can see here that the DNA molecules are precipitating out of the solution, which is seen as the web like substance.

 

Procedure can be found here.

Tips:

  • Ensure that the buffer is made ahead of time.
  • Ensure the isopropyl alcohol is COLD.
    • Leave it in the freezer over night.
    • Keep on ice during the lab
    • Make sure to pre-chill the pipette by pulling the isopropyl up and down through the pipette a couple of times. This ensures that the room temperatures pipette does not ruin the product.

Bellow is the resulting DNA, which we can scoop our of the solution in one big clump.

 

DNA Molecule Model (Grade 9)

In this model we use:

  • Pipe cleaners are the strength of the back bone
  • We use colored Twizzlers as the sugar (blue in video) and phosphate (purple in video)
  • Toothpicks represent the Hydrogen bonds within the nucleotides
  • Mini marshmallows as the 4 different colored nucleotides.

Have students mark with sharpie A,T,G,C on the nucleotides to assess their understanding of base pairing.

Notice in the video below, that the pipe cleaners provide a flexible enough backbone that we can twist the model into a double helix.