1887

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

    Authors: Joshua Ernest Kouassi1, Ingrid Waldron1,‡, Manuela Tripepi1, Mechthild Pohlschroder1,‡,*
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    Affiliations: 1: University of Pennsylvania Biology Department, Philadelphia, PA 19104
    AUTHOR AND ARTICLE INFORMATION AUTHOR AND ARTICLE INFORMATION
    • Received 08 July 2016 Accepted 24 October 2016 Published 21 April 2017
    • ©2017 Author(s). Published by the American Society for Microbiology.
    • [open-access] This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial-NoDerivatives 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/ and https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode), which grants the public the nonexclusive right to copy, distribute, or display the published work.

    • Supplemental materials available at http://asmscience.org/jmbe
    • *Corresponding author. Mailing address: 415 University Avenue, Philadelphia, PA 19104. Phone: 215-573-2283. E-mail: pohlschr@sas.upenn.edu.
    • I. Waldron and M. Pohlschroder contributed equally to this work.
    Source: J. Microbiol. Biol. Educ. April 2017 vol. 18 no. 1 doi:10.1128/jmbe.v18i1.1202
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    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.

Key Concept Ranking

DNA Repair
0.6760784
Halobacterium salinarum
0.55
DNA
0.50097734
Genetic Code
0.46689078
Ionizing Radiation
0.46480393
0.6760784

References & Citations

1. Clancy S2008DNA damage and repair: mechanisms for maintaining DNA integrityNature Educ11103
2. Friedberg EC2003DNA damage and repairNature42143644010.1038/nature0140812540918 http://dx.doi.org/10.1038/nature01408
3. Baliga NS, Bjork SJ, Bonneau R, Pan M, Iloanusi C, Kottemann MCH, Hood L, DiRuggiero JMay2004Systems level insights into the stress response to UV radiation in the halophilic Archaeon Halobacterium NRC-1Genome Res141025103510.1101/gr.199350415140832419780 http://dx.doi.org/10.1101/gr.1993504
4. Freeman S, Eddy SL, McDonough M, Smith MK, Okoroafor N, Jordt H, Wenderoth MP2014Active learning increases student performance in science, engineering and mathematicsPNAS1118410841510.1073/pnas.1319030111 http://dx.doi.org/10.1073/pnas.1319030111
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2017-04-21
2017-09-21

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.

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Figures

Image of FIGURE 1

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FIGURE 1

UV light can induce the formation of a thymine dimer. During photorepair, the enzyme photolyase uses energy from visible light to break the abnormal bond in the dimer and restore the DNA to its original normal structure.

Source: J. Microbiol. Biol. Educ. April 2017 vol. 18 no. 1 doi:10.1128/jmbe.v18i1.1202
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Image of FIGURE 2

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FIGURE 2

Design of experiment that demonstrates photorepair. Populations of are exposed to similar doses of UVC, and half of the populations recover in visible light so photorepair can occur.

Source: J. Microbiol. Biol. Educ. April 2017 vol. 18 no. 1 doi:10.1128/jmbe.v18i1.1202
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Image of FIGURE 3

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FIGURE 3

Protection from UVC light. The UV exposure box, made from a photocopy paper box and a clamp lamp, minimizes any risk of UV exposure for the students.

Source: J. Microbiol. Biol. Educ. April 2017 vol. 18 no. 1 doi:10.1128/jmbe.v18i1.1202
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Image of FIGURE 4

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FIGURE 4

Photorepair of UV-induced mutations increases survival of . Notice the increased survival of when 20, 30, or 40 seconds of UVC exposure was followed by one hour of sunlight exposure to allow for photorepair.

Source: J. Microbiol. Biol. Educ. April 2017 vol. 18 no. 1 doi:10.1128/jmbe.v18i1.1202
Download as Powerpoint

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