Magic Bullets: Chemistry vs. Cancer

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    The Gene Factor:
    Isolating DNA

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    Introduction
    General Safety Guidelines
    Teacher Preparation
    Notes
    Answers to Questions
    For more information at other Web sites...
    Relevant National Science Education Standards
    Relevant New Jersey State Science Education Standards

    Introduction

    This activity is included in the module to give students a chance to work with DNA and to convince them that the material actually exists. The procedure given here is one of many variations, using various foods as the source of the DNA.

    Teacher Preparation

      1. Chop up an onion into chunks that are about 1 cm square. Store them in a sealed plastic bag.

      2. Prepare the salt-detergent solution by adding 10 ml of clear dish detergent and 10 grams of sodium chloride to 90 ml of distilled water.

      3. Prepare the meat tenderizer solution by adding 5 grams of kitchen meat tenderizer to 95 ml of water.

      4. Prepare the 5% salt solution by adding 5 g noniodized salt to 100 ml of distilled water.

      5. Prepare the phenol red solution (if necessary) by adding as much phenol red as fits on the end of a flat toothpick to 100 ml of distilled water.

      6. You can substitute a notched wooden skewer for the scored glass rod. A toothpick works if it is long enough.

    Notes

      1. Many procedures require 95% ethyl alcohol, but some allow isopropyl alcohol. Both, however, must be cold for use.

      2. Other DNA sources you might try: split peas, spinach, kiwi, chicken liver, broccoli, wheat germ.

    Answers to Questions

      1. Why did you mash the onion?

        To help break up the cell walls of the onion.

      2. Where does the DNA form in the mixture?

        It forms at the alcohol-water interface.

      3. What color is the solution when phenol red is added? What does this tell you?

        The solution turns yellow. This indicates that the solution
        is acidic, from which we infer DNA to be an acid.

    For more information, at other Web sites...

      DNA - Overview — a series of interactive games on DNA, from The Tech Museum of Innovation in San Jose, California.

      How to Extract DNA from Anything Living — a very simple DNA extraction with accompanying explanations from the University of Utah.

    Relevant National Science Education Standards

      Science as Inquiry — The lab is an inquiry into a method used in modern science.

      Life Science — The major topic for this lab is DNA, the molecule that determines heredity.

    Relevant New Jersey State Science Education Standards

      5.1 The lab is problem-based.
      5.5 The lab involves DNA, the basis of heredity in all living things.
      5.6 The lab demonstrates the chemistry of isolating DNA from living tissue.

     

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