Strawberry Smoothies and Pea Soup

Smoothie DNA: Isolation of DNA from Strawberries

modified for CHEM 2090 by Koni Stone

Materials:

Directions:

  1.  Mash the strawberries in the beaker.
  2. Add an equal amount of water, several squirts of shampoo and a spoonful of salt.
  3. Stir gently.
  4. Strain the mixture through a wet paper towel or cheesecloth, you will get a clear fluid.
  5. Pour an equal amount of ice-cold alcohol into the fluid, you will see a cloud form.
  6. Take a chopstick and twirl it inside the cloud to observe long, gooey strings of nucleic acid (DNA.)

Pea Soup: Isolation of DNA from Split Peas

Materials:

Directions:

  1.  Blend peas, salt, cold water in a blender on high for 15 seconds.
  2. Strain the pea soup. Add 15 mL of shampoo to the liquid and stir gently.
  3. Pour aliquots into test tubes or small beakers.
  4. Add a pinch of enzymes to each test tube, let sit for a couple of minutes.
  5. Pour an equal amount of ice-cold rubbing alcohol down the side of the tube. You will see a cloud form.
  6. Take a chopstick or stirring rod and twirl it inside the cloud to observe long, gooey strings of nucleic acid (DNA.)
    7.

Background:

The woman behind the scenes

Rosalind Franklin made crucial contribution to the discovery of DNA although her name did not appear in the Nobel Prize awarded for this achievement. Her X-ray diffraction pictures of DNA were used by James Watson, Francis Crick and Maurice Wilkins as they correctly predicted the structure of DNA.  Rosalind was was working on the possible structure of DNA and even suggested the double helix structure but she did not publish her hunches, she was a very meticulous scientist and was doing very thorough analyses of her x-ray crystallography data.  Even though they were working in the same lab, at King's College in the University of London, personality differences precluded Franklin and Wilkins from being collaborators.  Thus, Wilkins showed her data to Watson and Crick (without her consent or knowledge) and this allowed them to complete the puzzle utilizing 3-D molecular models.

The Nobel Prize that went to Watson, Crick and Wilkins for the discovery of how DNA encodes information that is passed from one generation to the next.  This prize was awarded in 1962, four years after Franklin died from ovarian cancer.  The Nobel prize is not awarded posthumously, and it is awarded to no more than three scientists.  Thus, there is some controversy over whether she would have shared the prize if she had lived long enough.  

Reference:
McGrayne, Sharon Bertsch, Nobel Prize Women in Science, Carol Publishing Group, New York, 1993 pp 304-332.

Using sentences in well organized paragraphs, answer these questions in your conclusion.

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last edited on May 24, 2006