Assignment: Teaching Students To Apply Metabolic Pathways

In the Classroom

“Design Your Own Disease” Assignment: Teaching Students To Apply Metabolic Pathways Nick Flynn Chemistry and Biochemistry Department, Angelo State University, San Angelo, Texas 76909 [email protected]

A major focus of biochemistry courses is teaching metabolic pathways. The temptation is to require students to memorize pathways and regurgitate them on exams or quizzes. Although this approach has its function in regard to preparing premedical students for medical school, if overused it risks diluting student interest in an important area of biochemistry. The chemicaleducation literature describes some alternate approaches to teaching metabolism, though, arguably, additional engaging approaches are needed. Given that biochemistry is often taken during the students' fourth year, it is also important to teach biochemistry students scientific literacy and concepts of peer review (1). An assigned project in a second-semester biochemistry course is described that addresses these needs in an interesting manner that engages students and helps to prepare them for postgraduate work in biochemistry or related fields. This assignment, Design Your Own Disease, requires students in a second-semester biochemistry course to design a disease based on information discussed throughout the course. In this respect, the assignment is unique in that it requires students to apply concepts related to metabolic regulation, biochemical pathways, and disease processes. Current Use of Diseases in Biochemistry Courses A review of the education literature indicates that there is some limited use of diseases to teach biochemistry. Genetic diseases, for instance, have been used to teach students about protein structure (2). Similarly, sickle cell anemia is often used to teach students about protein structure and oxygen physiology. Hemoglobin and structural variants of hemoglobin are also used in biochemistry lab courses to teach students about ligand binding and protein oxidation (3). Additionally, some instructors employ the use of case studies in lab courses (4, 5). Current Approaches To Teaching Metabolism Several approaches to teaching metabolism have been described. A very interesting and timely approach involves the use of biochemical pathways to argue against the intelligent design theory (6). Here, the authors suggest that if intelligent design were involved in constructing metabolic pathways, the pathways would have been much more efficient. Another avenue of instruction involves the use of science fiction (e.g., a metabolic wonderland) to tap into the imagination of students and maintain their interest when discussing thermodynamics (7). The metabolism of ethanol to acetaldehyde by alcohol dehydrogenase has often been used as a comfortable transition from organic chemistry to biochemistry and metabolism by presenting students with familiar terms and concepts (8). The detoxification

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of xenobiotics provides another interesting discussion in metabolism that bridges the gap between biochemistry and physiology (9). Computer simulation of familiar metabolic pathways (10) and tracer studies of glycolysis in biochemistry laboratories have also been used to teach students about metabolic pathways (11, 12). Another approach utilized fruit spoilage to employ critical thinking and “get students thinking about what they are learning” in regard to metabolism (13). Focused approaches to select metabolic concepts have been employed but a broader treatment of metabolic pathways and, in particular, the application of those concepts is lacking. Scientific Literacy and Peer Review Students who take biochemistry courses are often close to graduating and thus need to be taught aspects of scientific literacy, peer review, and critical thinking. The one example of this approach in a biochemistry course is an assignment that required students to analyze data from the primary literature with an emphasis on data interpretation, critical analysis, and writing skills (1). There are other examples that accomplish these goals in other chemistry courses. An assignment in a quantitative analysis course focused on introducing students to the scientific literature because most students take this course during their undergraduate curriculum (14). Other assignments add a component concerning the peer-review process. This includes an organic chemistry assignment where peer reviews are used to provide feedback prior to turning in the final draft of the paper (15) and an assignment focused on interdisciplinary peer review between second-year chemistry students and first-year English composition students (16). Yet another assignment employed the use of peers to assign grades to laboratory reports (17). The need to emphasize scientific literacy and peer review is apparent from these articles; however, the use of metabolic pathways to accomplish this in a biochemistry course has not been given sufficient focus or emphasis. The Assignment The first use of the Design Your Own Disease assignment in the biochemistry course was as an extension of a requirement for students taking the course for graduate credit that had been used in prior years. There are three phases associated with this assignment. In the first phase, students choose a biosignaling mechanism from five primary areas in the textbook: G-proteins, receptor tyrosine kinases, oncogenes, gated ion channels, or transcriptional regulation by steroids. In the second phase, the students use this mechanism to propose a new disease process that is associated with one of the regulatory steps of a metabolic pathway

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r 2010 American Chemical Society and Division of Chemical Education, Inc. pubs.acs.org/jchemeduc Vol. 87 No. 8 August 2010 10.1021/ed100279z Published on Web 05/17/2010

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Journal of Chemical Education

799

In the Classroom

covered in class and present the information as a paper. Finally in the third phase, students peer review three student papers using three biosignaling mechanisms that they did not use in their own paper. Students are provided with the same grading rubric that the instructor uses to assign grades. Requiring students to declare a biosignaling mechanism early in the assignment has the advantage of encouraging students to initially think about the assignment several weeks before it is due. It also encourages students to pay more attention to biosignaling mechanisms that are presented during lectures. Several parameters are associated with the assignment to encourage students to use the primary literature and to apply much needed critical-thinking skills (18). Students must first identify an existing disease process associated with a regulatory step in a metabolic pathway and develop a bibliography concerning the disease, thus, requiring a review of the scientific literature. They must then apply information learned in class to develop a new disease process associated with this same regulatory step. Furthermore, students must indicate which age subset would most likely be affected and how the new disease would be detected and distinguished from the existing disease process. Finally, students are required to indicate how the new disease would be treated and how the existing disease is treated. These additional requirements also help develop critical-thinking skills and encourage students to review the scientific literature and evaluate relevant Web sites (19). The final phase of the assignment, peer review, has two main purposes. The first purpose is to reinforce biosignaling mechanisms by requiring students to evaluate student papers using biosignaling mechanisms that they did not use in their own paper. As part of the peer-review assignment, students assign a grade to each of the three papers that they review. They also provide a detailed explanation of the biosignaling mechanism used in each paper that they review. This condition requires students to review these biosignaling mechanisms both as an aspect of the peer-review portion and as a direct requirement of the assignment. It is important to emphasize that the instructor should reserve the right to modify peer-assigned grades and, most significantly, deduct points for erroneous peer assessments. By doing this, the importance of the peer-review process to scientific development is emphasized, thus teaching students that there are professional consequences to providing inaccurate or improper peer review of scholarly work. Possible Modifications of the Assignment Several modifications have been considered or previously utilized for this assignment. These include the use of guest speakers, further refinement of the peer-review process, and removal of the biosignaling-mechanism requirement. Guest speakers could be brought in to emphasize selected portions of the assignment. For example, a guest speaker from a medical laboratory could discuss the use and development of medical diagnostic tests and students could, in turn, be required to describe their diagnostic process in greater detail. A genetic counselor could also be invited to speak to the class and students could be required to discuss how their disease would be genetically detected. Similarly, a physician or group of physicians who treat particular population subsets (e.g., geriatric, pediatrician, general practitioner) would make excellent speaker choices that could be parlayed into requiring students to provide greater detail in describing which population subset is affected. 800


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Vol. 87 No. 8 August 2010

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Table 1. Grading Rubric for the Design Your Own Disease Assignment Evaluation Parameter

Possible Points

Peer review

30

Proper use of biosignaling mechanism

20

Distinguished from existing disease

15

Overall quality

15

Key regulatory step with associated disease

10

New disease process that involves this step

10

Detection

10

Population subset affected and why

10

Treatment of new disease

10

Treatment of old disease

10

Detailed bibliography

10

In addition to speakers, the peer-review process could be modified in several ways. Students could be required to only review papers that utilize the biosignaling mechanism that they chose. The advantage to this approach is that students would become better experts in this mechanism and their peer reviews would likely be more detailed. Students could also be provided with greater details concerning the peer-review process utilizing a rubric or evaluation instrument adopted from a peer-review process used by a scientific journal. An author's guide could be utilized that first requires students to develop their papers according to this guide and then requires students to conduct peer reviews using the author's guide as a basis of review. Finally, students could just be assigned one paper to evaluate alongside the instructor and then be required to provide an independent follow-up evaluation after modifications have been made by the original author. Although the peer-review process is an easy choice for modification, the removal of the biosignaling mechanism as a requirement is a more difficult one. The advantage of removing this requirement is that it opens up the assignment to more possibilities for the students and more permutations regarding effects on the regulatory step. The drawback is that less course material is emphasized, and this approach will likely require more extensive refinement of student papers as they are being developed. Grading It is suggested that a rubric be used to grade student papers for two important reasons. The first reason is that there are many permutations related to student choice of biosignaling mechanism and regulatory step. Some of these are complementary whereas others will make completing the assignment on a satisfactory basis more challenging. The second reason is that students can utilize the rubric in their peer-review process thus increasing the chance that their suggested grades would more closely match grades that the instructor would assign. A grading rubric based on a 150 point system is provided in Table 1. Scope of the Course and Assignment To help place the results of this assignment within the context of the course, course demographics are provided in Table 2. Roughly half of the students taking the course are interested in attending medical school. In addition to using medical applications

pubs.acs.org/jchemeduc

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r 2010 American Chemical Society and Division of Chemical Education, Inc.

In the Classroom • The assignment offered students an excellent blend of good, hard science with the freedom to be creative. • The project forced me to take apart one particular metabolic pathway and examine it for minute details. • While I was tinkering with an existing disease to create a novel one, I had to step back from time to time to determine the manner in which my modifications would manifest themselves at the level of the organism.

Table 2. Course Demographics for Last Three Years Major

Percentage of Class

Biochemistry or Chemistry

40.00

Preveterinarian or Animal Science

23.08

Biology

32.31

Other

4.61

Premedicine (independent of major)

47.69

Table 3. Comparison of Exam Scores and Class GPAs Exam

Prior to Design Your Own Using the Design Your Own Disease Assignmenta Disease Assignmenta

One

70.7 ( 2.3

72.8 ( 2.3

Two

70.0 ( 2.4

69.7 ( 2.2

Three

73.0 ( 2.5

75.1 ( 2.7

2.3 ( 0.2

2.7 ( 0.2

Class GPA

Conclusion

a Results between groups are not statistically different as analyzed by students' unpaired t test. Results are expressed as average ( SEM.

to metabolic pathways, I also emphasize research applications of metabolism within the course (tracer methodology, history of nitric oxide research, etc.). Results The Design Your Own Disease assignment has been utilized for three years. Class data have been analyzed over a six year period: three years prior to using the Design Your Own Disease assignment and three years using the Design Your Own Disease assignment. Thirty-eight students took the course for the threeyear period prior to initiating the assignment and 50 students took the course when the Design Your Own Disease assignment was utilized. Averages of exam scores and class GPAs are presented in Table 3. Whereas exam scores and class GPAs were not statistically different, student interest has increased in regard to lecture sessions that describe biosignaling mechanisms used in metabolic pathways. In both cases, student interest was measured based upon the relative number of material-associated emails, normalized on the basis of email traffic. More than twice as many material-associated emails were received following the implementation of the Design Your Own Disease assignment. Similarly, students pay more attention to regulatory steps in pathways during the early part of the semester when more challenging regulatory schemes are being introduced. Student interest and answers concerning regulatory steps of metabolic pathways for this past year was demonstrated by the observation that only 15% of the regulatory questions used on exams were missed by a majority of the students. Students interested in medically related professions enjoy the assignment and often contact our premedicine advisors to express this satisfaction while they are attending a medically related professional school. Student comments concerning the assignment were recently solicited and a representative sample of these comments is as follows: • It was a very good way to integrate all of the biochemical systems we learned. • It brought the entire semester's worth of learning into perspective, was a great review for the end of the course, and a different, yet effective, way of viewing biochemical pathways.


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Furthermore, a student who is attending graduate school recently indicated how useful the assignment is to prepare for application of concepts as opposed to regurgitation of knowledge found in graduate school.

A new approach to teaching students how to apply information concerning metabolic pathways is introduced. Although certain concepts related to metabolic pathways may require the rote approach to both instruction and learning, this assignment provides a more creative, applied outlet for students. In turn, it teaches students aspects concerning metabolic pathways and biosignaling mechanisms in an interesting manner. It has also provided insight into which pathways or biosignaling mechanisms are more popular with students. This has resulted in a greater emphasis on these interesting pathways and mechanisms throughout the course. Students find the assignment to be a fresh “deviation” from the standard science research paper that emphasizes literature review or research-proposal development (1). Acknowledgment I would like to thank the students in CHEM 4332, Intermediary Metabolism (Biochemistry II), who have taken this course from 2007-2009. Their comments concerning the Design Your Own Disease assignment as well as the class in general have led to the development and improvement of this assignment. Literature Cited 1. Lillig, J. W. J. Chem. Educ. 2008, 85, 1392–1394. 2. Schneider, T. L.; Linton, B. R. J. Chem. Educ. 2008, 85, 662–665. 3. Hanson, R. W. J. Chem. Educ. 1981, 58, 75–76. 4. Dinan, F. J. J. Coll. Sci. Teach. 2005, 35, 27–29. 5. Heidemann, M.; Urquhart, G. R. J. Coll. Sci. Teach. 2005, 35, 40–44. 6. Behrman, E. J.; Marzluf, G. A.; Bentley, R. J. Chem. Educ. 2004, 81, 1051–1052. 7. Aledo, J. C.; Esteban del Valle, A. J. Chem. Educ. 2002, 79, 1336– 1339. 8. Feinman, R. D. J. Chem. Educ. 2001, 78, 1215–1220. 9. Cullen, J. W. J. Chem. Educ. 1987, 64, 396–399. 10. Tirri, L. J.; Jurutks, P. W. J. Chem. Educ. 1986, 63, 1071–1073. 11. Taber, R. L.; Harwood, B. G. J. Chem. Educ. 1983, 60, 249– 250. 12. Giles, B. J.; Matsche, Z.; Egeland, R. D.; Reed, R. A.; Morioka, S. S.; Taber, R. L. J. Chem. Educ. 1999, 76, 1564–1566. 13. Shmaefsky, B. R. J. Coll. Sci. Teach. 2005, 34, 64–65. 14. Roecker, L. J. Chem. Educ. 2007, 84, 1380–1384.


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15. Shibley, I. A., Jr.; Milakofsky, L. K.; Nicotera, C. L. J. Chem. Educ. 2001, 78, 50–53. 16. Widanski, B. B.; Courtright-Nash, D. J. Chem. Educ. 2006, 83, 1788–1792. 17. Margerum, L. D.; Gulsrud, M.; Manlapez, R.; Rebong, R.; Love, A. J. Chem. Educ. 2007, 84, 292–295.

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18. Jacob, C. J. Chem. Educ. 2004, 81, 1216–1223. 19. Moore, J. W. J. Chem. Educ. 2008, 85, 1307.

Supporting Information Available Student handout, including the peer-review evaluation. This material is available via the Internet at http://pubs.acs.org.


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Assignment: Teaching Students To Apply Metabolic Pathways

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