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Cool Tool: DNA Sequencing Films
Type: Model/Demonstration
Topic: The DNA Code, DNA Sequencing, Mutations
Grade Level: High School
Contributor: Nancy Hutchison
School: Fred Hutchison Cancer Research Center, Seattle, WA
Purpose: To show that the DNA code is made up of four bases: A, T, G, and C. To show how to read a DNA sequence. To demonstrate the imperfection of authentic laboratory data.
Materials: X-ray films from radioactive DNA sequencing.
Methods: Show students the ladder of bands made by the DNA sequencing process. Point out the different lanes for A, T, G, and C. Have students "read" the sequence, starting from the bottom and working their way to the top. If possible, provide a side-by-side comparison of wildtype and variant/mutant sequences. Point out ambiguities in the sequence, e.g. where a particular band is in two or more lanes, and discuss possible ways to resolve the questionable bases. Such ambiguities are an excellent example of the real life difficulties that scientists encounter in the lab.
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last updated 06/15/04