&SOCIETY CONNECTING BIOTECHNOLOGY. A recombinant DNA activity allows students to consider the benefits and costs of genetic engineering

Transcription

1 CONNECTING BIOTECHNOLOGY &SOCIETY John McLaughlin and George Glasson A recombinant DNA activity allows students to consider the benefits and costs of genetic engineering Keyword: Genetic engineering/recombinant DNA at Enter code: TST To keep up with the ever-increasing student diversity in the science classroom, teachers must embrace the notion that science is a human endeavor (NRC 1996, p. 200). From this perspective, students learn how people from all cultures contribute to science and the role of science as a part of social and cultural traditions. Scientific educators agree that the socioscientific aspect of laboratory activities is essential in the education of a scientific, literate citizenry. Science teachers can help students come to the realization that science is a social endeavor and, while scientific research is empirically based, they will understand how the processes of science can still be defined and affected by human creativity (Zeidler et al. 2002, p. 345). As with scientific research, laboratory activities are more authentic if scientific concepts are embedded in issues affecting students everyday lives. 48

2 CDC Recombinant DNA (rdna) laboratory activities can be adapted to provide a unique opportunity for students to explore socioscientific issues through biotechnology. Biotechnology and society Biotechnology provides a rich domain from which teachers can facilitate student exploration of the social and ethical implications of science. Carefully designed lessons emphasizing nature of science ideas provide an intersection between scientific research and the effect of this research. In laboratories, geneticists join sections of DNA using enzymes through a process commonly called gene splicing providing opportunities for biotechnological applications in the fields of medicine, botany, and ecology. All of this research provides hope, but at what cost? Changes in the genetic code of an organism will undoubtedly affect the gene pool. We now must consider the fact that humans can make changes to genotypes with less time for consideration of ethical and ecological implications. Each change has potential consequences to life on Earth. Participation in biotechnology labs can clarify the scientific concepts involved, and clear up misconceptions, while giving students an opportunity for inquiry investigation and further exploration of societal issues affecting their lives. To determine the impact biotechnology may have on global societies, students should understand the biology concepts, consider the costs and benefits of the technology, and formulate statements supporting their ethical decisions. Equally important for students is the opportunity to experience both the actual laboratory procedure as well as the guided practice at formulating ethical questions. In the following sample lesson, teachers guide students through a biotechnology lab demonstrating rdna technology, followed by researching and comparing case studies and interviews. In this way, students: (1)Understand the science involved in rdna technology; (2)Develop an appreciation for the complexities of socioscientific issues; and (3)Conduct benefit cost analysis that supports individual decision-making strategies for understanding issues raised by biotechnology. Gene splicing lesson This lesson follows the 5-E Learning Model: Engage, Explore, Explain, Extension, and Evaluate (Bybee 1993). The model is designed to actively involve students in the inquiry process by accessing prior knowledge, utilizing strategies for scientific investigation of evidence, testing ideas, and reflecting on the results of investigations. Engage: Asking questions about scientific practices Students should begin by creating a Know-Wonder-Learn (KWL) chart to identify possible misconceptions and questions they may have about recombinant gene technology and its social implications. These charts consist of three columns. Column K (know) includes knowledge that students already have concerning science concepts and the benefits and costs of using recombinant technologies. Column W (wonder) includes questions students formulate throughout the course of the lesson. Column L (learn) consists of information students learned at various stages of the lesson. KWL charts also allow students to map their own progress through the questioning process when learning about biotechnology and socioscience issues. As the National Science Education Standards state, Skilled teachers guide students to understand the purpose for their own learning and to formulate self-assessing strategies (NRC 1996, p. 42). By sharing these charts in the classroom, teachers can encourage dialogue on research possibilities from different perspectives. In class discussions, students can encourage classmates to formulate new questions and reformulate older ones. Students can keep these charts accessible and continuously record new ideas and questions. These charts are excellent tools to help students see how scientists and members of society are asking and answering questions about scientific practices. Explore: rdna technology Beginning biology students have problems with scientific concepts in biotechnology because the processes of genetic recombination occur at a micro level. In order to demonstrate to students the recombinant process occurring throughout the lab, students first construct models representing both human DNA and plasmid DNA with paper onto which the DNA sequences have been copied (Kreuzer and Massey 1996). Students should understand that plasmids are small circular molecules of double stranded DNA derived from bacterial cells. A piece of DNA can be inserted into a plasmid if both the circular plasmid and the foreign piece of DNA have recognition sites for the same restriction enzyme. The plasmid (carrying genes for antibiotic resistance) and the foreign DNA (the gene of interest) are cut by a restriction enzyme producing intermediates with sticky and complementary ends. Those two intermediates recombine by base-pairing and are linked by DNA ligase. A new plasmid containing the foreign DNA as an insert recombinant DNA is obtained. To simulate this, using scissors as restriction enzymes students cut strips of the foreign DNA and plasmid DNA at different places and reattached complementary sticky ends together (with tape representing ligase) creating an rdna plasmid DNA from two or more sources spliced together. From this exercise, students generate questions about the recombinant processes (Figure 1, p. 51). Next, students explore rdna technology in the lab by building authentic recombinant plasmids. April

3 CDC ONCE STUDENTS HAVE TRANSFORMED PLASMIDS, THEY MAY BEGIN TO UNDERSTAND HOW THIS TYPE OF TECHNOLOGY MANIPULATES THE GENE POOL AND THAT ITS IMPLEMENTATION IS A HUMAN CHOICE. In this experiment, students are given two plasmid samples one that includes an antibiotic resistance gene for ampicillin (pamf), and another one that includes an antibiotic resistance gene for kanamycin (pkan). These plasmids are digested in separate restriction reactions to open up the plasmids, and then combined with foreign DNA to make rdna. The rdna is then added to an E. coli suspension and transformed the new recombinant plasmids are introduced into bacterial cells to transform the bacteria culture and produce many copies of the inserted DNA. The transformed suspension, as well as a control suspension, are plated on both plain agar and agar with antibiotics (ampicillin and kanamycin). Safety Note: Because this lab requires very careful procedures in order to avoid culturing environmental bacteria, it is safer to do this as a teacher demonstration unless students are exceptionally well prepared and sure to follow directions. Aseptic technique must be followed at every step of the lab exercise, and the final plates must be disinfected prior to disposal. Explain: Analyzing bacterial cultures Students observe experimental plate growth, compare the experimental growth to control plates, and make inferences about transformation and the success of the recombination processes. For example, students infer that successful transformation and recombination result in bacterial growth on experimental plates. When the transformed suspension is exposed to the antibiotics, all the bacteria cells not encoded by the plasmid DNA recombinant are killed, only the bacteria containing the rdna grows a cell culture containing the desired rdna is achieved. So, if bacteria is growing on the plates exposed to antibiotics, then the plasmid digestion and transformation was successful students have introduced DNA into another organism and cloned the DNA. Through open-ended questioning and recording observations on the KWL charts, teachers can direct students to make connections between introducing rdna into another organism and how this may change the phenotypical expression of that organism through empirical evidence of the growth of the bacteria culture. A change in the genetic make-up of the E. coli changes the viability and the physical features of the organism. As students work through this lab, they will gain a better understanding of the science behind recombinant technology, sterile technique, and bacterial transformation. Extension: Social research of biotechnology issues Using the KWL charts, teachers should encourage questions about the social implications of rdna technology. Teachers can engage students in socially relevant discourses about the nature of science. Once students have transformed plasmids, they may begin to understand how this type of technology manipulates the gene pool and that its implementation is a human choice. If it is a human choice, then how are these choices implemented in our society? Students can explore the Ethics and Issues page of the Access Excellence website at org/ab/ie to compare views they have formulated on how rdna technology relates to society with the essays and case studies located on this site. Through open-ended questioning and classroom discussion, teachers can direct students to make the connections between the increasing complexities of biotechnology questions with examples outside of the school laboratory. Teachers may also encourage students to interview members of their community such as organic farmers, pharmacists, or hospital workers who have varied opinions about topics in biotechnology. By making a general list on the KWL chart of benefits and costs of rdna technology as well as identification of stakeholders involved with biotechnology, students will better develop an appreciation for the complicated social and scientific issues that biotechnology presents to the public. Through class discussion and web-based research, students analyze the benefits and costs for the applications and issues involved with bioengineering of food and plants. Students also can search newspapers and periodicals for articles that voice different opinions. Teachers and students can examine these articles for scientific validity 50

4 FIGURE 1 Student example of KWL chart. Science concepts 1 Recombinant DNA technology allows you to combine DNA strands for desired results. What the student questions 1 How does the process work chemically? 2 What procedures are necessary to complete the lab? 3 Why do specific enzymes cut DNA strands in different places? 1 The isolated gene of interest and the plasmid DNA are cut by restriction enzymes, leaving sticky ends, which are reattached (by ligase) to each other because of complimentary bases. 2 The rdna plasmid is placed in a bacteria cell and the bacterium is grown in culture. 3 The copies of the gene are then isolated, and transferred to other organisms, or protein products are isolated and developed. Benefits: Bioengineering of food and plants 1 This technology can aid in the field of medicine and agriculture. What the students questions 1 How specifically does the field of human health/ nutrition benefit from rdna technology? 2 Exactly how and why are foods genetically enhanced? 3 Are there legal issues involved with recombinant technologies? 4 How does this technology affect me personally? 1 Plants are easy to grow and are resistant to disease. 2 Technology allows farmers more control over crops. 3 Process is possible solution to world hunger. 4 It is acceptable to genetically change plants if those changes could occur in nature. 5 Legal issues slow down biotechnological advancements. 6 Food can be more nutritious with less saturated fats and more needed vitamins. 7 Less water would be needed for agricultural use. Costs: Bioengineering of food and plants 1 Technology is very costly. 2 Technology is still experimental. What the student questions 1 Should consumers be notified about genetically altered foods? 2 Will this technology have a huge financial effect on society? 3 Are there health risks with this technology? 4 Will this technology affect the food web? 1 Labeling of many genetically altered foods is voluntary. 2 Altered plants could lead to the creation of new plant viruses. 3 Some people, who understand recombinant technologies, may reject its applications to food because of personal values. 4 Thirty-six common vegetables, dairy products, and processed foods have been genetically engineered and now contain genes from viruses, bacteria, insects, flowers, and animals. 5 Genes can transfer to non-target species if the environment isn t controlled. 6 Companies are not required to publish the results of their safety tests. 7 Stronger pesticides will spread into water supplies. 8 Technologies need more testing. April

5 FIGURE 2 Evaluation and student evidence. Scientific concepts and processes 1. Students will make predictions based on prior knowledge. 2. Students will be able to collect and record scientific data. 3. Students will make observations. 4. Students will develop a richer understanding for the complexities of the relatedness of biotechnology and society. 5. Students will develop an understanding of the social implications of rdna technology. through classroom discussion. In this way, the students interpretation of the observable data becomes apparent. Through the KWL chart, students develop a table of science concepts and benefit-cost of current rdna research (Figure 1, p. 51). Beginning with students prior knowledge and progressing to what was learned, teachers can assess student understanding of genetic concepts and laboratory procedures. Evaluation: Students refine KWL charts Within the 5-E Learning Cycle Model, evaluation information may be collected within laboratory procedures by means of KWL charts. Teachers can identify the scientific inquiry competencies (concepts and processes) addressed in the charts as evidence that students have met the particular competencies (Figure 2). This evidence also provides an empirical basis of students questioning the social implications of rdna technology and a better understanding for the complexities of these relationships. Classroom considerations Logistically, many teachers find the issue of time to be a crucial factor in choosing to implement socioscience issues in the classroom in addition to laboratory activities. With the technical protocols that biotechnology demands of both the classroom teacher and students, time may not permit for these valuable socioscience lessons in a contentoriented, standards-based curriculum. Even if teachers value addressing socioscientific issues in the classroom, they must implement strategies to guide students through the lesson in a timely and efficient manner. When time constraints are a factor, teachers may make the mistake of depending on the students to guide themselves through Evidence 1. Students will construct KWL charts. the process of developing supporting statements for making ethical decisions about the social implications, which the lab encompasses. However, students require the same type of direction as they are working through the formulation of these decision-making processes as they did for the learning of scientific concepts and investigating in the laboratory. Ignoring the facilitation of students ethical decision-making processes can lead to many student misconceptions about the nature of science and how it relates to the world around them. In general, students have rather simple and naive ideas about the interactions between science and society (NRC 1996, p. 1997). For example, when left on their own to construct ethical decision-making strategies, students may have little information from which to ask a question or base a decision and may be inclined to simply follow existing laws or rely on technological solutions (Wertz 1996). By teaching the science of biotechnology in the context of socioscience issues, students may be better able to understand the benefits and costs of science from which to base their ethical decisions. Students may also learn to raise ethical questions that relate to how science affects the autonomy, social justice and lives of others. 2. Students will have transformed bacteria plates and KWL charts. 3. Observation notes and meta-cognitive process should be recorded during lab. 4. Students will present different views on the costs and benefits of rdna technology. 5. Students will note similarities in their questions on their KWL charts and expository writings to those in case studies and essays. John McLaughlin ( jomclau1@vt.edu) is a biol- ogy teacher at Lord Botetourt High School, 1435 Roanoke Road, Daleville, VA 24083; and George Glasson ( glassong@vt.edu) is an associate pro- fessor of science education at Virginia Tech, Department of Teaching and Learning, Blacksburg, VA References Bybee, R An Instructional Model for Science Education. Developing Biological Literacy: A Guide to Developing Secondary and Post-secondary Biology Curricula. Colorado Springs, Colo.: Biological Sciences Curriculum Guide. Kreuzer, H., and A. Massey Recombinant DNA and Biotechnology. Washington, D.C.: ASM Press. National Research Council (NRC) National Science Education Standards. Washington, D.C.: National Academy Press. Wertz, D. C Ethics: What is it and why is it important? ethics.cfm. Zeidler, D., K. Walker, W. Ackett, and M. Simmons Tangled up in views: Beliefs in the nature of science and responses to socioscientific dilemmas. Science Education 86(3):