In the Classroom
Making the Most of a One-Semester General, Organic, Biochemistry Course: A Novel Integrated Curriculum1 Laura DeLong Frost and S. Todd Deal* Department of Chemistry, Georgia Southern University, Statesboro, GA 30460; *
[email protected] Patricia B. Humphrey Department of Mathematical Sciences, Georgia Southern University, Statesboro, GA 30460
Georgia Southern University offers a one-semester General, Organic, and Biochemistry course (CHEM 1140) that fulfills the chemistry requirement for nursing majors and is also required as the first of two chemistry courses taken by nutrition majors. In the past the standard curriculum for this course consisted of mostly general chemistry topics and as much organic chemistry as the instructor could fit into the course before the semester ended. The course syllabus followed the chapters in a typical general, organic, and biochemistry (GOB) textbook marketed for a two-semester course. A search of the chemical education literature on this type of course and experience in teaching not only the GOB course but also upper-level organic and biochemistry courses indicated that the GOB course content needed to purposefully emphasize biochemical topics and to include organic chemistry “as needed” to relate these topics. Chemistry educators and the American Chemical Society (ACS) have had a long history of concern and debate regarding course content in the chemistry courses taken by allied health professions students, especially nursing students (1–5). A survey published in 1992 by Walhout and Heinschel (4) indicated that biochemical topics such as metabolism and protein structure appear to be very important to nursing department heads and practicing nurses; however in many GOB courses these subjects do not get covered because of time constraints. In contrast, organic chemistry topics appeared to be of little importance to both practicing nurses and nursing department heads, but for some reason chemistry educators spend a lot of time on organic nomenclature and reactivity. In a separate study conducted around the same time, Dever found that teaching faculty in the allied health disciplines feel that chemistry educators “spend too much time on organic chemistry” (3). To address many of these concerns, the ACS Task Force on Chemical Education for Health Professions, appointed in the Fall of 1979, suggested that chemists teaching a one-semester course to these students consider the following: • Relate the topics in the course to the health sciences • Realize that the biochemistry section is the most important section to these students • Communicate with your health professions department regarding the content of your course • Realize that this may be the only physical science class that these students will ever take
The Task Force also compiled a list of topics that should be included in the course. Additionally, they made the fol-
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lowing observations regarding health professions students (1): They are often poorly prepared; Typically they are apprehensive about the course; Their motivation is often low; and Many of them are nontraditional students (i.e., over 23 years of age). In reforming CHEM 1140, these suggestions and observations from the literature have been considered and implemented as follows. First, the discussion of biochemical topics has been integrated throughout the syllabus. Findings from meetings with the Georgia Southern nursing faculty agreed with the literature in that the course should emphasize biologically important molecules and their function, not strictly organic reactions. Second, the course segment dealing with measurement and unit conversion has been moved into the laboratory portion of the course. Traditionally, this section appears at the beginning of most textbooks and is usually one of the first roadblocks that students who are poorly prepared in mathematics encounter in the course. In the integrated curriculum, topics are now covered in two, three-hour lab periods giving plenty of time for individual questions and assistance from both the instructor and upper-level undergraduate lab assistants. Third, several of the laboratory exercises have been revised in an effort to make the labs more biochemical in nature and more relevant to allied health professions. According to the literature, allied health faculty indicate that chemistry lab techniques and experiments typically found in GOB lab manuals are of very little importance to them or their students (3). In addition, the first hour of the lab period has been converted into a recitation session. This seemed like a better use of the students’ time since none of the current labs require the full three-hour lab period. No new material is covered during this hour; instead, it serves as a question and answer period for the students and a focused pre-lab discussion. Attendance at the recitation is required. Finally, a molecule project reported by Tracy (5) has been adapted and incorporated into the course in an attempt to tie many of the course topics together in a meaningful way for the students. Integrating the Curriculum While it is understood that certain topics cannot be omitted from a chemistry course, this curricular reform was designed to de-emphasize some topics and integrate others in order to create a curriculum that provides the necessary fundamentals of chemistry, while also including topics most relevant to the health science student.
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In the Classroom
Topics that were indicated as important in previous studies (2, 5) include atomic structure, bonding, equilibrium, acids and bases, intermolecular forces, and solution chemistry. The goal of the integrated curriculum is to provide adequate and appropriate coverage of each of these concepts (and many others), and to do so in a manner that enables students to develop not only an understanding of the concept being presented, but also the ability to apply the concept across areas of chemistry. Additionally, whenever appropriate, concepts and their applications are developed around examples or within contexts that are particularly relevant to allied health students. The presentation of covalent bonding in the integrated curriculum is a good example of the integration of topics from general and organic chemistry. In the revised curriculum, covalent bonding and Lewis structures are covered early in the semester (the first few weeks) with a focus on the Lewis structures of organic functional groups. This integration of organic functional groups into the discussion of bonding and Lewis
structures allows for the introduction of organic structures early in the course and focuses the students’ understanding of bonding on molecules that they will see throughout the course. In turn, the early introduction to organic structures allows for development of this content into more detailed discussions of complex molecules, namely the biomolecules. The first in-depth discussion of biomolecules in the course involves carbohydrates (typically around the 6th or 7th week). This presentation utilizes the previously developed concepts of molecular structure, polarity, and reactivity and expands these into a discussion of the reaction of carbonyls and alcohols to form hemiacetals. In turn, this leads to a discussion of ring formation, anomers, and disaccharide formation via a dehydration–condensation reaction—the majority of which are topics that are covered late (if ever) in the typical GOB course. Further treatment of chemical reactivity focuses on condensation and hydrolysis reactions, which are prevalent in each of the classes of biomolecules; alkene hydrogenation,
Atomic Structure A fundamental discussion of the parts of the atom focuses on understanding and deriving nuclear and electronic information from the periodic chart. This includes a brief presentation of nuclear chemistry and radioactivity. Ion formation and the octet rule are also presented, with a return to the periodic chart as the focus of understanding of these concepts.
Solutions The presentation focuses on percent concentrations, including introductions to the concepts of equivalents and moles. A discussion of osmotic pressure, osmolarity, diffusion, and dialysis is integrated into the presentation.
Chemical Bonding After a brief consideration of ionic compounds, the focus is on covalent bonding and the sharing of electrons, which is developed into the concepts of electronegativity and bond polarity. The concepts of bonding are developed into Lewis structures and formal charge with a focus on hydrocarbons, typical bonding patterns of non-carbon atoms, molecular polarity, and a discussion of VSEPR in the context of carbon compounds. These concepts are then used as a foundation for a presentation of Lewis structures of other organic functional groups, isomerism, and stereochemistry. Carbohydrates In-depth consideration of the first class of biomolecules builds on the concepts of functional group Lewis structures and chirality to discuss Fischer projections and ring formation. The latter topic, being one of the first examples of a chemical reaction considered, is developed around the concepts of polarity and opposites attracting. The concepts presented in ring formation are then developed into a discussion of disaccharides and polysaccharides. Intermolecular Forces An introduction to the types of forces moves quickly to contextual applications, including discussion of solubility and soap, boiling points, melting points, and cell membrane structure and function. A discussion of hydrogenation reactions of unsaturated fats is included in the melting point presentation.
Acids and Bases An introduction to the basics of acid–base chemistry is developed into conjugate acid–base theory, which facilitates presentation of equilibrium, pH, buffers, and LeChâtelier’s principle. Amino acids are the featured molecules throughout the discussion. Proteins The discussion of amino acids provides an excellent foundation for an in-depth presentation of protein chemistry, including peptide bond formation and the structural hierarchy of proteins. Of course, the latter draws strongly from and more thoroughly develops the concepts of intermolecular forces. Enzymes Building on the concepts of protein structure, this discussion emphasizes functional considerations and facilitates a thoroughly integrated treatment of reaction energetics. Nucleic Acids The coverage of nucleic acids includes discussions of DNA, its formation via condensation reactions, its structure (again highlighting intermolecular forces), and how that unique structure is responsible for the formation of proteins. Recombinant DNA technology and cloning are also discussed. Metabolism The capstone for the curriculum, this discussion draws on the majority of the concepts presented and re-integrates them to fully develop the concepts of biomolecules as energy yielding compounds. The presentation includes metabolic considerations of carbohydrates, proteins, and fats as well as discussions of obesity, dieting, and fitness.
Textbox 1. Abridged syllabus for the integrated one-semester GOB course with topics briefly described.
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In the Classroom
which is integrated into the discussion of the physical state versus structure of fats and oils; and oxidation and reduction reactions, which are discussed in the context of metabolic reactions. The concepts of energy of a reaction and activation energy are presented in the context of enzymatic catalysis. In each of these examples and for the entire curriculum, the integration of the topics sets the stage for an easy transition to a discussion—in greater depth than was previously possible—of the structure and reactivity of the four major groups of biomolecules. Relating the general and organic chemistry topics to the biomolecules and integrating all of these topics into a coherent presentation has increased student interest in the course, as discussed later. Textbox 1 presents an abridged syllabus listing some of the topics that are discussed in the approximate order of presentation, demonstrating the integrated nature of the curriculum. While none of the currently available textbooks offers an extensively integrated presentation as outlined here, most of them can be adapted for use by selecting appropriate topics and sections of the text. In summary, our goal in the redesign of the curriculum was to develop a course that incorporates these important objectives to: • Allow for a more in-depth discussion of the chemistry of the biomolecules and to begin that discussion earlier in the course • Provide coverage of the necessary and relevant topics from the traditional general and organic chemistry parts of the course • Integrate the discussion of topics from the three traditional areas (general, organic, and biochemistry) into a seamless whole • Develop concepts, whenever possible, around examples and applications particularly relevant to health science students
Each of these goals focuses on developing the desired student learning outcomes—to develop a broad understanding of chemistry as an integrated subject and to develop the ability to apply fundamental chemical principles. Both of these skills are essential for students to be able to understand and interpret the structure and reactivity of molecules, particularly the biomolecules.
Other Course Revisions to the Laboratory In order to enhance the focus on biochemistry, two laboratory experiences with a biochemical focus have been added to the laboratory curriculum. The additions include an experiment involving the separation and identification of glucose from a piece of candy and hydrolyzed starch via liquid chromatography, and the well-known enzyme activity assay utilizing polyphenol oxidase (tyrosinase) that students isolate from potatoes and then determine substrate specificity. The former experiment is a modification of the lab by Selfe (6) and nicely follows the introduction to carbohydrates in lecture. Both of the experiments serve to introduce the students to relevant biochemical techniques through simple, dependable experiments. The Molecule Project In an effort to tie together several course topics in a meaningful manner, Tracy’s “Molecular Model Project” (5) was adapted as a capstone project and renamed simply the “Molecule Project”. Each student is assigned a biochemically active molecule from a list of molecules developed by the instructor. The student is asked to undertake a number of tasks with their assigned molecule: 1. Provide the Lewis structure for the molecule 2. Identify its organic functional groups 3. Identify any chiral centers present in the molecule 4. Provide a computer-generated, three-dimensional perspective ball-and-stick model of the molecule in color 5. Predict the molecule’s solubility in water 6. Provide a summary (no more than one double-spaced, typed page) of the molecule’s biological function, including at least one chemical reaction of the molecule 7. Include any references used in compiling the report
Moving Measurement to the Laboratory As mentioned previously, unit conversion and measurement appear at the beginning of many GOB textbooks. Beginning a semester with this subject can “turn off ” many students who have poor mathematics skills (1). To address this, these topics were removed from the classroom and made the focus of two consecutive lab periods. The rationale for the move was that the extended laboratory period would provide time for individual, intensive instruction for those students who needed it, while the flexibility and informal setting of the laboratory venue would allow the better-prepared students to complete their assignment without being held back by those who needed the extra help. The laboratory sections
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consist of the same 48 students in the lecture section and employ two upper-level undergraduate chemistry majors as lab assistants. This arrangement creates a more supportive learning environment by providing three “instructors” who can address student questions on an individual basis. The two laboratory exercises focus on basic units of measurement, fundamental physical quantities, and an introduction to the metric system and unit conversion.
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Tasks 1–3 are turned in during the course of the semester for preliminary grading as the pertinent material is discussed in the course. Student Responses to the Course Evaluation Student feedback on the integrated curriculum has been positive. Student evaluation data using the end of semester course evaluation instrument have been compiled for all offerings of the course between Spring 2001 and Fall 2003. This period was chosen because half of the 14 offerings of the course during this time, 7 sections with 351 students, used the “standard” curriculum while half of the offerings, 7
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In the Classroom Table 1. Comparison of Student Interest in Chemistry Before and After the Course, by Curriculum Type Scale for Rating Student Interest a 5
04
03
2
1
Standard: Before (N = 204)
11
047
079
39
28
Standard: After (N = 204)
21
064
063
30
26
Integrated: Before (N = 285)
09
059
125
56
36
Integrated: After (N = 288)
46
Fraction of Students (%)
Curriculum Type and Condition
standard (F'00) integrated (F'02) integrated (Sp'03)
30
20
10
0 F
117
081
27
D
C
B
A
Grade
17
The scale ranged from 5, “very interested” to 1, “no interest at all”.
Figure 1. Grade distribution of students taught with the standard versus the integrated curriculum.
sections with 354 students, used the “integrated” curriculum. Readers should note that given the experimental nature of the integrated curriculum, no faculty member was required to use it, and some chose not to do so during this “test” period. In the data presented, three faculty members chose to use the standard curriculum, two chose to use the integrated curriculum, and one used both, adopting the integrated curriculum after it was more completely developed. The data presented in this paper represents responses from 200 students for the standard curriculum and 280 students for the integrated curriculum. (Evaluations are given on a randomly chosen day near the end of the semester and are not announced ahead of time. The difference between the number of enrolled students and the number of evaluation responses is one simply of student attendance.) The assessment of the integrated curriculum began with an attempt to determine the effects, if any, of the curricular change on student interest. Two questions from the course evaluation instrument asked students to indicate their interest before and after taking the course. Using a standard 1–5 Likert scale, students gave a ranked response to “What was your level of interest in this subject before taking this course?”, and “What was your level of interest in this subject after taking this course?”. The data, shown in Table 1, were analyzed with χ2 tests of homogeneity, which test whether or not the observed differences in cell counts (number of responses for each of the ratings 1–5) are due to randomness or some systematic difference in the underlying distributions. Larger χ2 values indicate larger differences in the distributions. In these tests small p-values indicate any observed differences are not due to randomness and large p-values indicate that the observed difference is due to mere chance. Briefly, the data indicate that the students coming into the course using either curriculum had similar attitudes toward chemistry (χ2 = 6.63, p-value = 0.6219). The students completing the course under the standard curriculum gave responses showing very little change in attitude, either positive or negative (χ2 = 8.78, p-value = 0.0669). In fact, when the differences in individual scores are examined, the interest in chemistry decreased by an average 0.17. However, students completing the course under the integrated curriculum
had a significant, positive increase in their attitude toward chemistry (χ2 = 73.01, p-value = 5 ⫻ 10᎑15). The mean difference for individual students was 0.71. Comparison of these average interest level differences using a two-sample t-test yields highly significant results (t = 7.98, p-value = 1 ⫻ 10᎑14). Since cultivating student interest in our subject is a primary goal of the course, these data indicate that the integrated curriculum has been successful. Further, when analyzing the data for the standard curriculum, it was discovered that student attitudes at the end of the course were instructor-dependent (χ2 = 17.08, p-value = 0.0090), whereas student attitudes under the integrated curriculum were independent of the instructor (χ2 = 8.73, p-value = 0.3656). While positive results in terms of student interest are often attributed to professor enthusiasm, these data seem to indicate that the improved attitudes are a result of interest generated by the integrated curriculum, not the instructor. Despite the fact that neither common final exams nor entrance and exit exams are administered in this course (which would allow a quantitative assessment of student grades and learning), one of us (LDF) did have student achievement data from an offering of the course prior to Spring 2001 (using the standard curriculum) to compare to courses taught using the integrated curriculum. Figure 1 is a graphical representation of the grade distribution of three offerings of the course—one using the standard curriculum, and two using the integrated curriculum. All three offerings of the course had similar numbers of students enrolled (~50). The figure shows that for the courses taught using the integrated curriculum, the peak in the grade distribution is shifted toward the “B” range as compared to the peak of the distribution using the standard curriculum. The figure also shows fewer grades below the “C” range for the courses taught using the integrated curriculum. Interestingly, the curves for the two most recent offerings of the course (using the integrated curriculum) show remarkably similar distributions. While it is difficult to draw definitive conclusions from information such as this, the improved grade distribution (also reflected in an average GPA of 2.66 for the integrated curriculum and an average GPA of 2.31 for the standard cur-
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In the Classroom
riculum), which was maintained over two separate offerings of the course, supports the course evaluation data that interest in the subject matter has increased because of exposure to the integrated curriculum. Finally, the student withdrawal rates for the 14 sections of the course were calculated and these numbers showed that students taught using the integrated curriculum were slightly less likely to withdraw from the class (23 out of 354: 6.5%) than students taught using the standard curriculum (34 out of 351: 9.7%). Again, these data seem to support the course evaluation data.
this material. While poorly prepared students still struggle with the mathematics, the individualized instruction that the laboratory venue allows has, at the very least, seemed to relieve some of their frustration. Finally, the molecule project has served very well as a capstone experience, allowing students to apply what they’ve learned in the context of a “reallife” molecule. The integrated curriculum is clearly superior to the standard GOB curriculum in terms of coverage possible and student interest, and is easily adaptable to fit a variety of institutional types. Note
Conclusion The introduction of an integrated curriculum into the GOB course at Georgia Southern University has been well received by the students, as indicated by the improved course evaluations measuring student interest. The integration of topics from general and organic chemistry into the discussion of biochemistry has provided for a more complete and in-depth coverage of the biomolecules and their chemistry than was previously possible. This curriculum has the advantages of covering topics of major interest to allied health students and faculty while not excluding topics of fundamental importance to a thorough understanding and appreciation of the chemistry involved. Moving the discussion of the measurement and unit conversion concepts to the lab has given the students a context for developing their understanding of
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1. This paper was initially presented at the 18th Biennial Conference on Chemical Education, Ames, IA, July 2004.
Literature Cited 1. Treblow, M.; Daly, J. M.; Sarquis, J. L. J. Chem. Educ. 1984, 61, 620–621. 2. Williams, D. H. J. Chem. Educ. 1987, 64, 707–709. 3. Dever, D. F. J. Chem. Educ. 1991, 68, 763–764. 4. Walhout, J. S.; Heinschel, J. J. Chem. Educ. 1992, 69, 483– 487. 5. Tracy, H. J. J. Chem. Educ. 1998, 75, 1442–1444. 6. Selfe, S. Laboratory Manual for Blei and Odian’s General, Organic, and Biochemistry; W. H. Freeman and Sons: New York, 2000; pp 195–200.
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