In science, there are few ideas more important or confusing than energy. This fact makes it difficult for instructors to teach ideas related to energy, especially in a way that is consistent across chemistry and biology. One particularly confusing topic is the role of adenosine triphosphate (ATP) in reaction coupling. While in biology it may be productive to discuss ATP hydrolysis, such a discussion can lead students to believe that it is the breaking of the “energy-rich phosphate bonds” that releases the energy, which directly contradicts how bonds and interactions are discussed in chemistry. Instead, we propose an alternate approach focusing on the causal mechanism which underlies this phenomenon. This requires a discussion of the transfer of a phosphoryl group from ATP to another molecule, creating a more reactive common intermediate that then goes on to produce the original thermodynamically unfavorable product. We developed an activity to both help students think about this mechanism and to probe how this approach impacts their understanding of ATP and reaction coupling. We administered this activity to students in undergraduate general chemistry, organic chemistry, molecular biology, and biochemistry courses. In this presentation, we will share the results of our analysis, highlighting both the challenges and successes in using this mechanistic approach. We believe this work can show that by focusing on the mechanism in which ATP activates other molecules through phosphorylation, we can provide students with a way to explain how ATP couples the reactions together, without invoking the troublesome idea of bond energies. Thus providing an important step towards our goal of helping students develop a robust understanding of energy that is coherent across the disciplines.

Characterizing biology and chemistry students’ explanations of the role of ATP in reaction coupling

ACS Spring 2022

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