The genes you know today may not be the ones you know tomorrow.Every semester, I start my introductory biology class with a discussion of why learning skills and habits of mind are more important than "facts" alone. To impress upon them that knowledge changes, I take advantage of the fact that I'm far more chronologically enhanced than my students and present examples of what I learned in introductory biology, and even in graduate school. That the theory of endosymbiosis was relatively new and the mechanism of chemiosmotic oxidative phosphorylation not yet taught impresses them little. That plate tectonics was relatively new impresses them a little more. However, when I tell them that (at least some of) the faculty who taught me, even in graduate school, earned their doctorates before the nature of DNA was understood, they are surprised and appear to understand the point that what they learn today may be completely revised in their lifetimes, and that learning is a lifetime endeavor. When I think about my professors, I also recall how, as a new faculty member myself, I began to become more cognizant of what I did not know as I began to teach, but still felt very current in my knowledge. I did not expect my knowledge to become dated; I expected to add to my knowledge, not replace it. In fact, I vowed that I would never let myself become a faculty member whose knowledge was out of date. Yet as time has passed, new discoveries have mounted up, and keeping up has become a great challenge. Even fundamental concepts, as I have introduced them in class, have changed. Here, I will use genes and inheritance as an example.
When I entered the (perhaps inefficient) phrase "What is a gene?" into my university's library search tool, it returned numerous articles with that title. An early one referred to a gene as a chemical entity located in chromosomes (Demerec, 1933), while another referred to it as only a concept (Malisoff, 1939). In Beadle's (1955) answer to the question, the mounting data indicated that DNA was clearly involved, but the evidence for the role of RNA was still being developed and transcription was not understood. He posed the question of whether a gene was a "functional unit carrying the information necessary for the synthesis of a macromolecule" or "the unit of recombination." Textbooks of my college era discussed genes in terms of proposed models of cistrons, recons, and mutons; were missing the start codon in charts of the genetic code; and listed "nonsense" for what we know as stop codons (Keeton, 1967). My recollection is of a gene changing from coding for one enzyme, to one protein, to one polypeptide. With time, we added discussions of regulatory genes, introns and exons (are they part of the gene or not?), post-transcriptional processing and splicing, and so much more. Contrasts are made between genes in the molecular sense and genes in the evolutionary sense (Falk, 2010). Recent works discuss different conceptualizations of the gene (Stotz et al., 2004) held by scientists or used in teaching (Gericke & Hagberg, 2006). Not surprisingly, these works also point out the effects such variations have on teaching, learning, research, and public understanding. New findings indicate that the role of genes and our understanding of inheritance are all the more complex, with RNA playing a greater role than expected, sections of DNA coding for more than one protein, overlapping genes, single genes being located on multiple chromosomes, and epigenetic inheritance (Pearson, 2006; Pennisi, 2007; Flannery, 2010).
Changes in our understanding of teaching and learning have also occurred over the years. While transmission of genetic information was thought of simply as transfer of chromosomes or genes or DNA, learning in the sense of transfer of classroom information from one generation (teacher) to the next (student) was thought to result from a simple description or explanation (written or oral) of the "fact" or concept. Perhaps analogous to discoveries of horizontal gene transfer, contextual or disciplinary differences in the definition of genes, and the influence of chemical and structural interactions affecting gene expression within or between generations, we now have a richer picture of learning and teaching that incorporates prior knowledge, peer-instruction, student engagement, visualization techniques, student-driven laboratory investigations, and more into a suite of tools used to promote conceptual understanding and scientific thinking among our students.
That is why I welcome this issue of ABT with its focus on genetics, and I think that you will too. The articles present a mixture of scientific theories and findings and teaching practices that will help you incorporate the latest content and skills into your classes. The discussions of epigenetics, bioinformatics, proteomics, and mitochondrial genetics will refresh or expand your understanding of these areas. At the same time, they will provide you with ideas for teaching in the laboratory or non-laboratory environment and resources for doing so. The laboratories outlined truly transform students from cooks following books into investigators pursuing one or another level of inquiry. Other articles describe visualization or manipulative enhancements that the authors have developed and effectively tested in their classes and that you can use to engage students in yours. One of the features of these articles is that while many of the authors have explicitly targeted both college and high school classes, all can be up-regulated or down-regulated to fit the needs of secondary and college instructors whether they instruct future biologists or non-scientists.
This issue underscores the importance of NABT and the ABT as the means of disseminating current content and pedagogical content knowledge and techniques. While reminding me of how my knowledge and skills can become dated without attention, it has helped to stem that decline by filling in some gaps in my knowledge and providing me with new ideas for my classroom. I hope it does for you as well. Finally, writing this has made me think of those who taught me and are no longer around to answer my questions as to whether they felt out-of-date. I am happy to salute them for never making me think that they had, and proud to be part of our association's work to keep us well informed.
Beadle, G.W. (1955). What is a gene? AIBS Bulletin, 5(5), 15.
Demerec, M. (1933). What is a gene? Journal of Heredity, 24, 368-378.
Falk, P. (2010). What is a gene?--revisited. Studies in History and Philosophy of Biological and Biomedical Sciences, 41, 396-406.
Flannery, M.C. (2010). Crazy genes. American Biology Teacher, 72, 258-260.
Gericke, N.M. & Hagberg, M. (2006). Definition of historical models of gene function and their relation to students' understanding of genetics. Science Education, 16, 849-881.
Keeton, W.T. (1967). Biological Sciences. New York, NY: W.W. Norton.
Malisoff, W.M. (1939). What is a gene? Philosophy of Science, 6, 385-389.
Pearson, H. (2006). Genetics: what is a gene? Nature, 441, 398-401.
Pennisi, E. (2007). DNA study forces rethink of what it means to be a gene. Science, 316, 1556-1557.
Stoltz, K., Griffiths, P.E. & Knight, R. (2004). How biologists conceptualize genes: an empirical study. Studies in History and Philosophy of Biological and Biomedical Sciences, 35, 647-673.
Donald P. French