Read the newest issue of the Journal of Microbiology and Biology Education, including Mierdel J, Bogner F. Simply ingen(e)ious! how creative DNA modeling can enrich classic hands-on experimentation. Below, authors Franz Bogner and Julia Mierdel discuss the creative modeling portion of their activity, and how it can be used in virtual learning.

Models and modeling play a central role in simplifying, illustrating and explaining complex themes and invisible phenomena, like those in molecular genetics. The discovery of the DNA-double helix in 1953 was an important milestone. Without completing their own experiments, James Watson and Francis Crick correctly interpreted the complex X-ray crystallography work of Rosalind Franklin and others by physically modeling DNA. The 1953 model demonstrated the stereochemistry of the atoms, which is hard for students to understand. We developed a hands-on exercise where students build their own DNA model using common, household materials. This activity is particularly useful during a time when most students are learning remotely because of COVID-19.

Students follow the footsteps of Watson and Crick in solving the molecular puzzle of the DNA structure. In preparation, students read an abridged version of the original letter Francis Crick wrote to his 12-year-old son in 1953. This text describes base pairing and the sugar and phosphate backbone of DNA. After reading, students answer comprehension questions. In the process of formulating their answers, they internalize essential background information and mentally begin to build their model.

Building the DNA Model

There are no limits to the ingenuity of students when building their DNA models with this learning activity. In the classroom, we provide students with a box of materials that includes pipe cleaners, modeling clay, beads, colored squares of paper and drinking straws. Students must decide which materials to use and how those materials will represent the individual components of DNA, as well as their relationships to one another. However, the model can also be realized at home with a variety of objects. For example, paper clips in different colors and sizes or different types of fruit gums or other sweets can be used to represent the various components, which can be linked with wires.

To self-evaluate their DNA models, students compare their model to a commercially-available model, like the Molymod mini-DNA model. Using the evaluation checklist, students recognize important features of the DNA structure in the picture of the commercial model and quickly check them on their own models (e.g., cohesion of the 2 DNA strands by hydrogen bonds, possible base pairings).

Assessing Student’s Knowledge of DNA Structure

Beyond self-evaluation, the learning activity provides a category system educators can use to assess the model quality. This system includes 5 analysis sectors (e.g., bases, primary structure) and grades the resulting models regarding the concrete representations and structural characteristics using sum scores (e.g., analysis sector BA1: 1 point for “symbolized bases” or 2 points for “symbolized and qualified bases;” max. 19 points). The most common errors in students’ models include the lack of representation of hydrogen bonds, incorrect linking of the sugar residues to the bases or incorrect turning of the helix (e.g. left-handed instead of right-handed helix).

We also developed a multiple choice evaluation with specific questions to assess student learning after the modeling activity. In our experience, having students build their own DNA model clearly builds their cognitive short- and mid-term learning, such as analytic, motoric, communication and reasoning skills.

The Journal of Microbiology & Biology Education (JMBE) features original, peer-reviewed articles that foster scholarly teaching, and provide readily adoptable resources in biology education, including the DNA model described above&mdashread more articles like these in the latest issue of JMBE.