Laboratory Activity to Promote Student Understanding of UV Mutagenesis and DNA Repair

Abstract

Changes in DNA molecules are common, due to the effects of UV light and other external and internal mutagens. Cells have a variety of repair mechanisms which serve to maintain the accuracy of the genetic code. This activity includes a low-cost, safe and technically feasible experiment, which allows students to observe the effects of UV mutagenesis and DNA photorepair in the halophilc archaeon, Haloferax volcanii. An optional extension links this activity to topics of immediate concern to students – how exposure to UVC light contributes to skin cancer risk and the protective effects of sunscreen. Students design and carry out an experiment to test whether SPF 15 sunscreen increases the lethal exposure time for H. volcanii by a factor of 15. Throughout the activity, discussion questions engage students in actively thinking about the biological phenomena and experimental procedures and analysis. This activity is designed for students in college or university genetics, microbiology, or introductory biology courses as well as in high school honors biology courses. Teachers report that this activity was valuable in helping students understand mutagenesis and photorepair and in developing student skills in designing and analyzing experiments.

From Gene to Function: A Safe Laboratory Exercise Promoting the Learning of the Central Dogma of Biology for the Undergraduate Biology Curriculum

“…The materials needed are available from commercial suppliers, and the two strains of H. volcanii are available for shipping, upon request, from Dr. Tripepi's Lab. An alternative to the regular lab medium has been published and offers a way to grow H. volcanii using ingredients available at grocery stores (6). Sterile technique is not required due to the nature of this halophile organism.…”