To understand genetics, students need to be able to explain and draw connections between a large number of concepts. The purpose of the study reported herein was to explore the way upper secondary science students reason about concepts in molecular genetics in order to understand protein synthesis. Data were collected by group interviews. Concept maps were constructed using the interview transcripts, and analysed. The most central concept was DNA, which served as a link between the concepts of genes and proteins. Students spontaneously introduced concepts from classical genetics to explain molecular genetics. The concept maps generated from the different group interviews were similar in that various concepts consistently appeared within specific subgroups of interconnected concepts, ie clusters. Five main clusters were identified. The students were better able to relate between concepts within a cluster than between concepts in different clusters. The clusters can be seen as representations of the students’ knowledge structures, and could be used as starting points in teaching genetics.

We recommend that courses in genetics should begin by focusing on students’ existing connections between concepts from different clusters and then point out concepts that feature in two or more clusters such as DNA, gene, and protein.

This study investigates how the domain-specific language of molecular life science is mediated by the comparative contexts of chemistry and biology education. We study upper secondary chemistry and biology textbook sections on protein synthesis to reveal the conceptual demography of concepts central to the communication of this subject. The term "conceptual demography" refers to the frequency, distribution, and internal relationships between technical terms mediating a potential conceptual meaning of a phenomenon. Data were collected through a content analysis approach inspired by text summarization and text mining techniques. Chemistry textbooks were found to present protein synthesis using a mechanistic approach, whereas biology textbooks use a conceptual approach. The chemistry texts make no clear distinction between core terms and peripheral terms but use them equally frequently and give equal attention to all relationships, whereas biology textbooks focus on core terms and mention and relate them to each other more frequently than peripheral terms. Moreover, chemistry textbooks typically segment the text, focusing on a couple of technical terms at a time, whereas biology textbooks focus on overarching structures of the protein synthesis. We argue that it might be fruitful for students to learn protein synthesis from both contexts to build a meaningful understanding.

This study provides insights into the use of metaphors in protein synthesis descriptions in upper secondary chemistry and biology textbooks. Data were collected from seven Swedish textbooks and analyzed with the Metaphor Identification Protocol and categorized within the framework of Conceptual Metaphor Theory. The results reveal two main parallel metaphor systems of construction-based metaphors and information-based metaphors. Five sub-systems with different emphasis on the usage of construction and information related metaphors emerged in the analysis: the location, translocation, transportation, cryptography and publishing sub-metaphor systems. These metaphors can function as double-edged swords for students' learning. On the positive side, the construction-based metaphors (location, translocation and transportation) meet the educational need to describe where the processes of the protein synthesis occur and how these take place, while the information-based metaphors (cryptography and publishing) describe how the different sub-processes of the protein synthesis are linked via the interflow of information between them. On the negative side, the identified metaphors are presented implicitly without explanations, thus making it difficult for the students to identify them. Also, textbook sentences often contain metaphors drawn from several of the five sub-systems, requiring students not only to differentiate between them, but also to connect the source and target domain of the different metaphors correctly. The results highlight the important role of the teacher in supporting students' learning by explaining what metaphors are and how they are used in textbooks. To further this end, authors of biology and chemistry textbooks are recommended to introduce metaphors early and explicitly.