Article Teaching Arrangements of Carbohydrate Metabolism in Biochemistry Curriculum in Peking University Health Science Center

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1 Article Teaching Arrangements of Carbohydrate Metabolism in Biochemistry Curriculum in Peking University Health Science Center Hao Chen Ju-Hua Ni* From the Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Xue Yuan Road 38, Beijing , People s Republic of China Abstract Biochemistry occupies a unique place in the medical school curricula, but the teaching of biochemistry presents certain challenges. One of these challenges is facilitating students interest in and mastery of metabolism. The many pathways and modes of regulation can be overwhelming for students to learn and difficult for professors to teach in an engaging manner. The first chapter of the metabolism section in current Chinese biochemistry textbooks covers carbohydrate metabolism. Medical students usually complain about the difficulty of this subject. Here we discuss how to facilitate learning by rearranging the subjects in this introductory chapter of biochemical metabolism and to lay a solid foundation for future study. The strategy involves reorganizing the order in which subjects are taught from simple to complex and from short to long metabolic pathways. Most students taking the curriculum consider that the strategy engages their learning interests in biochemistry and enhances their learning outcomes. VC 2013 by The International Union of Biochemistry and Molecular Biology, 41(3): , 2013 Keywords: biochemistry; carbohydrate metabolism; teaching Introduction Biochemistry is an important curriculum for all medical students. In most medical schools in China, it is taught in the first or second year of the courses. According to the specificity of this curriculum, it should include theoretical and practical knowledge related to cellular basis of physiological and pathological processes to human body functioning. These issues are of particular importance in multiple aspects for a deeper understanding of health-diseases processes and diagnosis [1 4]. In Peking University Health Science Center (PKUHSC), students in all majors are required to take biochemistry course as part of their basic medical courses. Before taking the biochemistry, all the students have to complete the prerequisite courses such as *Address for correspondence to: Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Xue Yuan Road 38, Beijing , People s Republic of China; juhuani@ bjmu.edu.cn. Received 7 December 2012; accepted 8 March 2013 DOI: /bmb Published online 4 May 2013 in Wiley Online Library (wileyonlinelibrary.com) inorganic chemistry and organic chemistry. Within medical disciplines, the motivation of students to study biochemistry may involve an innate desire for knowledge, to gain knowledge to inform future career roles and to pass assessments to progress on the course [5]. Biochemistry presents a relatively difficult subject to study. It contains an extensive list of terminology (names of compounds, enzymes, and metabolic pathways). A high level of abstract thinking might be required for understanding the perplexing contents [6 8]. To promote active learning of biochemistry, many creative strategies have been developed in recent years in different countries [1,5,9 11]. Biochemical metabolic pathways might seem, at first sight, to undergraduate students a confusing, incomprehensible mess of chemical formulae. There is no doubt that metabolic charts are complex, and many biochemists remember their introduction to metabolism as a puzzling and unforgettable experience [10]. In our current biochemistry curriculum, carbohydrate metabolism is always taught first in the section of metabolism (Table 1). Most students who learn metabolism by the traditional teaching approach face carbohydrate metabolism with terror. They do not understand the purpose of memorizing so many pathways and chemical structures in such a short period of time and do not integrate different pathways as they are in real life. Biochemistry and Molecular Biology Education 139

2 Biochemistry and Molecular Biology Education TABLE 1 Biochemistry topics taught and number of hours for these topics in PKUHSC (4 class hours/week) Biochemistry topics Hour (S) Introduction of biochemistry 1 The structure and function of proteins 3 Molecular composition of proteins, protein structure and function, protein physical chemical properties and purification The structure and function of nucleic acids 3 Molecular composition of nucleic acids, structures and functions of DNA, structures and functions of RNA, physical chemical properties of nucleic acids Enzymes 3 Molecular structure of enzymes, properties and mechanisms on enzymatic reaction, enzyme kinetics, regulatory of enzymes Carbohydrate metabolism 6 Normal level of blood sugar and its regulation, main pathways of carbohydrate metabolism Lipid metabolism 4 Triglyceride metabolism, phospholipid metabolism, cholesterol metabolism, lipid transport in plasma Biological oxidation 3 Electron transport chain, oxidative phosphorylation Amino acid metabolism 4 Dietary protein nutrition, general pathways of amino acid catabolism, ammonia metabolism, metabolism of individual amino acid Nucleotide metabolism 3 Metabolism of purine nucleotides, metabolism of pyrimidine nucleotides Integration and regulation of metabolism 2 Cellular signal transduction 4 Signaling pathways of membrane receptors, signaling pathways of nuclear receptors DNA biosynthesis 3 DNA replication, reverse transcription, DNA damage and repair RNA biosynthesis 3 Transcription, RNA processing, ribozymes, RNA replication Protein biosynthesis 4 The machinery of protein synthesis, process of protein synthesis, post-translational processing and transport Regulation of gene expression 4 Principles of gene regulation, regulation of gene expression in bacteria, regulation of gene expression in eukaryotes 140 Teaching Arrangements of Carbohydrate Metabolism

3 In this article, we take carbohydrate metabolism as an example to discuss how to help students with respect to learning of biochemical metabolism and improve learning efficiency by reorganizing the subject without increasing class time. Traditional Sequence of Carbohydrate Metabolism Instruction in Current Chinese Biochemistry Textbooks and Common Problems Current Chinese biochemistry textbooks deal with carbohydrate biochemistry in the following order: an outline of carbohydrate metabolism, glycolysis, aerobic oxidation, pentose phosphate pathway, glycogen metabolism, gluconeogenesis, and blood glucose regulation [12,13]. This presentation scheme emphasizes glucose as an energy source, with high-efficiency ATP production as its central fate. The phosphate pentose pathway, glycogen metabolism, and gluconeogenesis are treated as peripheral subjects. Although this arrangement gives prominence to the most key points, it also poses the following challenges: The first two pathways of carbohydrate metabolism presented in our current biochemistry textbooks are glycolysis and aerobic oxidation. The reactions involved in these two pathways are very complex and perplexing. Even though students have learned the knowledge of chemistry of proteins, enzymology, chemistry of nucleic acids, and vitamins before reaching this chapter, they have generally not been in contact with even one metabolic process before. Under these circumstances, if we begin with the complex subject, students will feel discouraged. They will find it very difficult to understand and memorize the many abstract concepts and metabolic reactions necessary to comprehending carbohydrate metabolism. Second, glycogen metabolism and the regulation of blood glucose levels, which are much simpler and easier to understand than other carbohydrate metabolic pathways, are presented in the last section of carbohydrate metabolism in our current biochemistry textbooks. These subjects can be used to pave the way for the overall study of carbohydrate metabolism from the perspective of dynamic balance. However, they cannot serve this purpose if they are taught last. Third, gluconeogenesis is the retrograde process of glycolysis, while there are three sections aerobic oxidation, the pentose phosphate pathway, and glycogen metabolism arranged between them in our current biochemistry textbooks. This does not facilitate the time-efficient memorization of information. (The pentose phosphate pathway is a branch pathway of glucose catabolism, and it is reasonable to teaching these two sections in succession, as in current textbooks.) In summary, the perplexing metabolic reactions of carbohydrate metabolism are taught first, and the short and simple metabolic pathways are taught last. This arrangement might make students feel confused, arouse psychological anxiety toward biochemistry, prevent them from forming a complete knowledge base, and make it more difficult to learn subsequent metabolic pathways. The study of biochemistry becomes a heavy burden. While carbohydrate metabolism is taught in accordance with the order in current Chinese biochemistry textbooks, students generally report the content is too abstract, there are too many reaction steps in each metabolic pathway. They feel it is difficult to study carbohydrate metabolism effectively and intuitively and to develop a firm grasp of the subject. Many of them report that only a vague impression of the subject matter remains after they complete their final exams. In view of this situation, we should reorganize the teaching sequence of this chapter. Reorganization of the Carbohydrate Metabolism Chapter and the Strategies Adopted Because of the problems mentioned above and for the convenience of teachers and students, we adjust the teaching sequence of subjects in the carbohydrate metabolism chapter as follows: metabolic pathways are now ordered from short to long; content is ordered from simple to complex; the content is portrayed in a coherent manner; emphasis is placed on logic. The specific adjustments made and strategies adopted are listed below. 1. After a brief introduction to digestion, absorption, and the physiological functions of sugars, blood sugar is explained. Because blood sugar is an extremely important medical concept, the normal range of blood sugar levels and the importance of keeping them stable are highlighted. The factors that maintain the dynamic equilibrium of blood sugar are described. Then the concepts of glycolysis, aerobic oxidation, glycogenesis, glycogenolysis, and gluconeogenesis are briefly introduced in succession. These concepts must be taught clearly, and the significance of various metabolic pathways is pointed out with respect to the maintenance of blood sugar equilibrium. This paves the way for the following introduction of various metabolic pathways. In this way, students can form a general idea of what metabolic pathways are and build themselves a framework, allowing them to take the initiative to study. Then the hormones that regulate blood sugar are briefly introduced and emphasis is placed on the signaling pathways involved, laying a foundation for next subjects. 2. Next, glycogenesis and glycogenolysis are explained. First of all, the physiological significance of glycogen Chen and Ni 141

4 Biochemistry and Molecular Biology Education storage is introduced, followed by the pathways of glycogenesis and glycogenolysis. Because this is the first time that students encounter with metabolic pathways, the structure of glycogen must be described clearly and emphasis must be placed on the structural changes that the product undergoes after every step. At the same time, teachers must help students review their existing knowledge, such as enzyme nomenclature. When introducing the regulation of glycogen metabolism, teachers must lead the students to review the knowledge of allosteric enzymes, allosteric regulation, and covalent modification. Because these two metabolic pathways are simple in concept and have few steps, the students may find the subject relatively easy to understand, with proper explanations of the structure of the metabolites interspersed with appropriate reviews of enzymology. This will also allow the students to grasp a learning method for the subsequent contents. 3. Glycolysis should be explained next. Glycolysis involves many reaction steps and many enzymes. Teachers should emphasize changes in the structure of metabolites after every step. Because the students have already been introduced to the metabolic field and because glycolysis can be regarded as an extension of glycogenolysis, students will learn these complex metabolic reactions easily by using methods with which they are already familiar. Next, gluconeogenesis can be introduced as the retrograde process of glycolysis because most of steps in the reaction are the inverse of the reactions in gluconeogenesis. This allows teachers to focus on the three steps that are irreversible. Teachers should cover the regulation of gluconeogenesis in detail. This includes the allosteric regulation of enzymes and regulation by hormone. These subjects can be considered expansions of previous concepts. This teaching sequence allows students to link the subjects together closely, and makes study more efficient and consistent. It may also help students fill the initial framework they set up in mind with specific contents. 4. Next, aerobic oxidation can be taught as an extension of glycolysis. Aerobic oxidation is the most complex pathway in carbohydrate metabolism, and the citric acid cycle is an amphibolic pathway serving in both catabolic and anabolic processes. Besides its role in the oxidative catabolism of carbohydrates, fatty acids, and amino acids, the cycle provides precursors for many biosynthetic pathways. Teachers should briefly outline aerobic oxidation for students, clearly point out the significance of the citric acid cycle, and emphasize the specific steps in that cycle that can generate energy. Finally, the pentose phosphate pathway can be briefly introduced as a branch of carbohydrate metabolism and its physiological function should be described. In this way, students will gradually acclimate to the highly abstract and complex metabolic pathways. They will then find them easier to FIG 1 Teaching arrangements of carbohydrate metabolism in biochemistry curriculum in Peking University Health Science Center. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] absorb and remember, and form a systemic knowledge of carbohydrate metabolism with glycolysis as its center. Although students often prefer to have material presented exactly as given in the textbook, they will not feel unsuited to follow the logic the teacher provided above. Our teaching arrangements of carbohydrate metabolism in current biochemistry curriculum are summarized in Fig. 1. A questionnaire designed to obtain feedback on student preferences for carbohydrate teaching methods was developed. Anonymous questionnaires were collected at the end of the course. The questionnaires for students in different academic years contained the same questions. Of 128 students surveyed, 94 students (73.4%) preferred the strategy described above. The students who preferred the new teaching arrangement think that the strategy can stimulate their learning interests in biochemistry and enhance their learning experiences. The average score of students on the final test taught by the strategy is significantly higher than those taught by traditional style (83.4% vs. 67.8%), thus indicating the strategy works better than traditional teaching sequence. We also compared the scores specific tested on the carbohydrate metabolism knowledge. The average 142 Teaching Arrangements of Carbohydrate Metabolism

5 FIG 2 The average score specific tested on the carbohydrate metabolism knowledge and the total average score of biochemistry final test across two consecutive academic years were compared by using a two-tailed t test. The exams used for the data were composed of different questions of the same difficulty level : students taking biochemistry course during academic year , taught by traditional style, n ¼ 279; : students taking biochemistry course during academic year , taught by the strategy described here, n ¼ 227. Values are means 6 SEM. * indicates p < with an overview of the situation, and then addresses every part in detail. Although Chinese biochemistry experts have adjusted introduction sequence of carbohydrate metabolism according to our Chinese thinking habits, there are still many problems in the way we teach this subject. Teachers must teach according to our students thinking and studying habits to make studying more effective. Edward Thorndike postulated three learning laws, one of them is the law of readiness. The law of readiness states that if you feel ready and exercise that feeling, it provides satisfaction; conversely if you force an action it provides annoyance [15]. When teaching carbohydrate metabolism, the simple and short metabolic pathways are introduced first, and the perplexing metabolic reactions are taught last to help students to gradually adapt to this subject. This arrangement matches the law of readiness. Biochemical metabolism covers about 40% of biochemistry content in current Chinese textbooks. The complexity of metabolic reactions, the abstract nature of the concepts, and the sheer numbers of different enzymes and factors involved in enzymatic catalysis can make learning biochemistry very difficult. When teaching these contents, teachers should create a logical progression of ideas and help students synthesize all the information so that they may build their own knowledge system. score of the traditional method was 62.7%, the average score of the new method was 72.9%. It is significantly higher average score in new methods group than in the traditional method group on the carbohydrate metabolism knowledge (Fig. 2). Discussion The textbook Lehninger Principles of Biochemistry divides the carbohydrate metabolism into three chapters. Glycolysis, gluconeogenesis, and the pentose phosphate pathway constitute one chapter. The regulation of metabolic pathways, coordinated regulation of glycolysis and gluconeogenesis, and glycogen metabolism in animals constitute another chapter. The citric acid cycle fills the third chapter by itself [14]. This biochemistry textbook is very different from our commonly used edition, which are edited by Peking University Medical Press and People s Health Publishing House in China [12,13]. Current research in many areas suggests that Western countries are still in leading position with respect to both classical knowledge and cutting-edge theory. When teaching and learning in China, we should pay careful attention to the differences in thinking style between Chinese and Western students. In the West, many forms of thinking are built around starting small and then growing. One problem originates from a small, gradual deduction, and finally forms a system. The Chinese way of thinking tends to work from large to small. It begins Acknowledgements The authors thank Ms. Guo-Shun An (PKUHSC, Beijing, China) for her kind assistant on the analyses of the questionnaires and test scores of students and Prof. Hong-Ti Jia (PKUHSC, Beijing, China) for manuscript editing. This work was supported by the National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China (Grant No. J /J0108, J /J0108). References [1] Novelli, E. L. B. and Fernandes, A. A. H. (2007) Students preferred teaching techniques for biochemistry in biomedicine and medicine courses. Biochem. Mol. Biol. Educ. 35, [2] Moreland, B. H. (1996) How much biochemistry should a good doctor know? Biochem. Educ. 24, [3] Wood, E. J. (1996) How much biochemistry should a good doctor know? A biochemist s viewpoint. Biochem. Educ. 24, [4] Feldberg, R. S. (2001) The new biochemistry: In praise of alternate curricula. Biochem. Mol. Biol. Educ. 29, [5] Gough, K. C. (2011) Enhanced podcasts for teaching biochemistry to veterinary students. Biochem. Mol. Biol. Educ. 39, [6] Wood, E. J. (1990) Biochemistry is a difficult subject for both student and teacher. Biochem. Educ. 18, [7] Matthews, J. C. (1997) Intermeshing passive and active learning strategies in teaching biochemistry. Am. J. Pharm. Educ. 61, [8] Silva, I. F. and Batista, N. A. (2003) Biochemistry in undergraduate health courses. Biochem. Mol. Biol. Educ. 31, [9] Bobby, Z., Radhika, M. R., Nandeesha, H., Balasubramanian, A., Prerna, S., Archana, N., and Thippeswamy, D. N. (2012) Formulation of multiple Chen and Ni 143

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