Genetics - DNA Sequencing Model Lab

DNA Sequencing Model Lab

Teacher: Sue Bonestroo
Subject: DNA, Genetics
Grade Level(s): 10 11 12
Target Audience: Biology I
Materials Needed: 4 one meter lengths of roll paper or tagboard (one each for A, T, C, G), 4 meter sticks, tape, 4 envelopes or beaker-like containers, overhead, paper and pencil
Class Time: 40 minutes
Brief Summary: Students pretend they are each genetic engineers with a test tube of unknown DNA (PCR'd) possibly taken from blood cells of someone with a genetic condition. A DNA sequence is displayed, and students write all segments possible if di-deoxy bases are added. These are torn (cut) and taped (poured) onto "gel" sheets at front of room into proper base size rows, then sequence.
Student Objective(s): To experience a method of DNA sequencing.
Integration (tying it all together): Begin with the reasons why DNA sequencing is occurring, especially as it ties in with the Human Genome Project. Apply DNA sequencing to other specific studies being done, and to the type of activities that they would do as geneticists, the time needed to do a complete gene, and the laboratory space, equipment, technology and supplies it involves.
Description of Activities: 1.) Students are to imagine steps they have gone through to isolate and perform PCR on their C-DNA and discuss. 2.) Place the large 20 base sequence of "unknown" C-DNA molecule on overhead (to be removed immediately after this step). Students, divided into 4 groups: A, T, C, G. They begin at the base of the molecule and replicate all possible sequences that could result with di-deoxy A's, T's, C's, G's. 3.) Students cut these into strips, write the number of bases on each, and put into their "test tube". 4.) Discuss electrophoresis and get students to conclude that smaller DNA segments will move more quickly before having them tape segments onto the proper number row of numbers 1 - 21 (with 21 at the top). 5.) Students read and write sequences and check with the original anti codons. 6.) Show the picture on the actual gel and sequence.
Further Information and References: I acquired several X-rays of gels from the University of Minnesota Genetics Research Project that I show to students.

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