2026 ASM Conference for Undergraduate Educators

Deoxyribonucleic acid (DNA) stores genetic information required for the development, function, and reproduction of all living organisms. The double helical structure of DNA is formed through complementary base pairing between nucleotides (adenine-thymine and guanine-cytosine). Because DNA cannot be directly observed with the naked eye, it can be difficult for learners to connect the structure with the biological functions. To reinforce undergraduate students’ understanding of DNA in a Bacterial Genetics course, we developed a tactile DNA Puzzle Builder activity that models how the structure of DNA supports its role as a genetic information storage molecule. The activity uses laser cut, color coded wooden puzzle pieces and an instructional guide that requires a foundational understanding of DNA structure. In the first phase, students assemble the four deoxyribonucleotide triphosphates (dNTPs) from their constituent components: a deoxyribose sugar, nitrogenous base, and three phosphate groups. In the second phase, students model DNA assembly by removing two phosphate groups from each dNTP and joining nucleotides through phosphodiester bond formation. Students then construct the complementary DNA strand by applying correct base-pairing rules and indicating hydrogen bonds. Finally, they identify the 5’ and 3’ ends of each strand to demonstrate strand polarity, a key concept in DNA replication. The activity can be completed in pairs or small groups, and individual models can be combined to generate larger unique DNA molecules at the classroom level. Student feedback was positive and assessment data from course quizzes indicated an improved understanding of DNA structure-function relationships. These findings suggest that hands-on, tactile learning activities can effectively reinforce foundational concepts in bacterial genetics.