Abstract:

DNA fingerprinting is often used in biology courses as it is an easy way to engage students in inquiry-based learning activities. However, despite repeated exposure, and maybe due to an exaggerated confidence in their own understanding of the topic, students are still facing some important misconceptions and poor understanding of the genetic concepts behind DNA fingerprinting. Among the misconceptions frequently seen are 1)- All the bands are unique to an individual; 2)- If you share bands, you are somewhat related; 3)-You have or you don't have a band. In addition, students often show a poor understanding or fail to make links between related concepts. For instance, almost none of them is - at start - able to apply the concept of homo/heterozygosity to the sequences studied in DNA fingerprints. They also have trouble stating what a band in the pattern really represents, and what makes the difference between bands. Finally, the concept of polymorphism, encompassing genetic variability and genetic unicity, is another unclear concept. Besides this, students often consider the topic easy and don't give it the necessary attention to fully understand it. For all these reasons, I developed a new DNA fingerprinting simulation easily done in class with paper cuts. Details can be found in a previous publication (Chamoux, HAPS educator 2017). The basic version of this activity was administered in a Cell/Molecular Biology course addressed to 1st/2nd year BSc Biology students. A total of 102 students were exposed to the activity, but submission of written answers was optional. An upgraded version of this activity, using genetic linkage as a basis, was developed and administered in an advanced Human Genetics course addressed to 3rd/4th year students (23 students did this activity). The activity was developed to specifically address the concepts of polymorphisms, homo/heterozygosity, the molecular nature of the bands seen in the DNA fingerprint pattern, relatedness, genetic variability and unicity. The activity includes several specific problem-solving questions and calculations and ends with several open questions. Ths activity not only acted as an eye-opener for many students who realized how quickly they were blocked in questions on topics that they considered acquired. Moreover, the activity generated very positive and engaging discussions among peers and with the whole classroom. I collected written answers and graded them according to the level of understanding demonstrated. Several weeks later, I included 3 comprehension questions on the same topic in the final exam. Results showed that students who had submitted written answers for the activity had, on average, higher marks on the 3 final exam questions than students who had not submitted answers. While I would like to conduct more tests, I consider this activity as a good mean to re-explore concepts that we often take for granted but that students don't master well in fact.

Keywords:

DNA fingerprints, misconceptions in genetics, active learning, genetic variability, polymorphism.