Lewis and Kattman ( 2004) report that the majority of British students in their study (age 14–16) state that genes are important for the determination of characteristics. However, according to Duncan and Reiser ( 2007) they are not explicitly taught how this knowledge can be used when explaining phenomena at the level of the cell or higher levels of biological organization.įor instance, in genetics education, it appears that the molecular details of DNA and proteins add very little to students’ understanding of genetic phenomena. Students learn the structure and properties of DNA, RNA and proteins and they are taught how DNA codes for RNA and proteins. In upper-secondary biology education, this macromolecular level is part of the curriculum. Our understanding of many biological phenomena that until recently could be described only at the level of the population, whole organisms or cells is now revolutionized with new insights at the macromolecular level (Moore 1993). 172) adds molecular-level details to phenomena that traditionally have been studied only at higher levels, such as embryology, neurobiology and evolution. This ‘molecularization’ of biology (Kay 1996 Morange 1998, p.
Many biological disciplines have extended their scope towards the molecular level. The heuristics that scientists use can help students to apply this intuitive notion to the levels in between molecules and cells. Education using molecular mechanistic reasoning can build on common intuitive reasoning about mechanisms. We suggest including molecular mechanistic reasoning in biology education and we identify criteria for designing such education. They subdivide a cellular activity into hypothetical lower-level activities (top-down approaches) and they predict and test the organization of macromolecules into functional modules that play a role in higher-level activities (bottom-up approaches). In molecular biological research, scientists use heuristics based on these intermediate levels to construct mechanistic explanations. We conclude that to describe cellular phenomena scientists use entities and activities at multiple levels between cells and molecules. Mechanistic explanations describe a phenomenon in terms of the entities involved, the activities displayed and the way these entities and activities are organized. We base this framework on recent work in the philosophy of science that characterizes explanations in molecular biology as mechanistic explanations. It represents both the general type of explanation in molecular biology and the research strategies scientists use to find these explanations. In this paper, we present a framework that could help students to reason back and forth between cells and molecules.
Recent studies suggest that students lack a framework to reason about complex systems to make this connection. Although molecular-level details are part of the upper-secondary biology curriculum in most countries, many studies report that students fail to connect molecular knowledge to phenomena at the level of cells, organs and organisms.