Separation of DNA fragments is carried out on 50 cm long denaturing gels, and the DNA bands are detected by the method just described. The students then interpret their sequencing data. Each high school classroom sequences at least two different subclones, and after the students have analyzed their data, they enter it into our directory. Introduction to the Experiment Prior to starting this lab, the teacher leads the students in a review of the concepts and techniques of DNA sequencing and interpreting a sequencing gel. A modeling exercise using pop-it beads is presented in the introduction to this experiment.
Students can also practice interpreting sequencing data using autoradiographs of sequencing gels.
This can be done in a 55 minute class period. This part of the experiment takes about 4 hours, so much of the process needs to be done outside of the class period. The gel apparatus is set up about 1 hour before class time, and the gel is allowed to pre-run in that time. During the class period, the students heat-denature their DNA samples, flush the gel wells, load their samples and start electrophoresis. The gels are typically run for about 2.5 hours, although the running times can be varied so that different portions of one DNA tract can be analyzed.