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
Nick.Flynn@angelo.edu
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
_
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
_
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
_
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
Journal of Chemical Education
_
Vol. 87 No. 8 August 2010
_
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
_
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.
r 2010 American Chemical Society and Division of Chemical Education, Inc.
_
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.
pubs.acs.org/jchemeduc
_
Vol. 87 No. 8 August 2010
_
Journal of Chemical Education
801
In the Classroom
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.
802
Journal of Chemical Education
_
Vol. 87 No. 8 August 2010
_
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.
pubs.acs.org/jchemeduc
_
r 2010 American Chemical Society and Division of Chemical Education, Inc.