Arthur W. Devor
The Ohio Stote University Columbus, Ohio 43210
I
I
wn InregraTea vrganlc mocnemmy Lourse
Durine the nast three or four decades. attempts havc heen mad; to offer short courses in chemistry to nursing students. several textbooks have been published for this purpose. These include introductions to inorganic, organic, and biochemistry, respectively. In recent years research in hiochemistw has been increased many-fold. Textbooks are now being published which include organic and biochemistry with general chemistry as a prerequisite. Two years ago a course was introduced at Ohio State University which includes pertinent organic chemistry as an integral part of biochemistry with principles of general chemistry as a prerequisite. This was introduced for students in our School of Allied Medical Professions. It seemed advantageous both didactically and economically to introduce the reactions given in an introductory organic chemistry course concurrently with the biochemical reactions responsible for body functions; the former subject matter was used to introduce the latter. The course content includes the following topics in the sequence given 1) Brief review of atomio structure and kinetic theory of molecules. 2) Structure of open-chain hydrocarbons. 3) Alcohols, aldehydes, and ketones as simple sugars. 4) Oxidation-reduction in terms of electrons m d hvdrogen . &toms. 5) Addition t o the double bond with introduction to cyclic structure of simple sugars. 6) Glycaside linkage in common food carhohydrates. 7) Water and water mixtures--solutions and colloids in nature. 8) Digestion of carbohydrates as hydrolysis of the glycoside linkage. Enzymes as catalysts. Absorption of carhohydrates. 9) Buffers and aH. 10) Phosphates in metabolizing cells, acids, esters, m d anhydrides. High energy bonds. 11) Reactions regulatifig blood sugar levels. 12) Energy from carhohydrates. The Emhden-Meyerhoff pathway and the citric acid cycle. 13) Further studies on pH and buffers. 14) Carbohydrates in biosynthesis. 15) Amines. amino acids. amides. and rotei ins with s ~ e c i a l referenee to food vdnes. Aromatic camoounds.
Absorption. 17) Nitrogen and sulfur metabolism. 18) Alpha keto acids for energy and glywgenesis. CO1 and K O formation. The cytochrome system. 19) Esters. auaternarv amines. and l i ~ i d swith emvhasi? on ' food akd tissueiipids. ' 20) Food digestion and methods of testing for enzymes and factors affecting enzyme activity. Absorption of dige+ tion products. This paper wa? presented before the Division of Chemical Education of the American Chemical Society, September 8, 1989.
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Fats for enerw. -" and biosvnthesis of fats. Blood, respir&m, and &id-base balance. Nuclcosides, nucleotides, and nucleoproteins. Further studies on coenzymes, eneymes, and vitamins in metabolism. 25) Metabolic functions of some of the amino acids. 26) One, two, and three carbon units in metabolism 27) Excretion products. 21) 22) 23) 24)
Alcohols, aldehydes, and ketones were introduced as groups found in the simple sugars. The students were required to use the commonly known simple sugars for practice in learning the structural formulas and configuration of stereoisomers. For example, removing hydrogen atoms from' the primary alcohol of glycerol (oxidation) yields the simple sugar called glycerose. Whereas, removal of hydrogen from the secondary alcohol yields the'ketotriose; at this time it is emphasized that these two sugars occur as phosphates in metabolizing cells of our bodies. Ribose (in RNA) is introduced with ribitol (in the vitamin called riboflavin). As an introduction to the cyclic structures (Fischer and Haworth) of sugars the principle of addition to the double bond was emdoved. The students were rerequired to write equ&ns involving addition of the alcohol to the aldehyde to form the hemiacetal. The a- and p-forms are discussed as occurring in equilibrium when in solution whereas in the solid state they are of the a- or p-configuration. After practice in writing the cyclic structures of the common monosaccharides, the structures and coufiguration of food oligo- and poly-saccharides were iutroduced as glycosides. The linkages occurring via the anomeric carbon were studied by removing an H and OH to give the specific bondings when illustrating the glycoside configurations. Digestion was emphasized as a hydrolysis (hydro for water and lysis for splitting) reaction requiring specific catalysts called enzymes. Prior to metabolism of carhohydrates, acids, ester, anhydrides, and high energy bonds were introduced. The reactions of metabolism were treated as organic reactions. The students were required to practice writing the equations the same as if they were studying reactions in an organic course. The principles of organic reactions were emphasized and repeated. For example, in a course in organic chemistry the aldol condensation is introduced. In this course it was introduced as a step in glycogenesis. Amines and amides (peptides) were introduced with the study of amino acids and proteins. Structures of amino sugars were not presented until the alpha amino acids were studied. Aromatic compounds were introduced with .the aromatic amino acid. Quaternary amines were studied as choline in lipids. Volume 47, Number 7, July 1970
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537
The malonic ester synthesis is important in the study of organic synthesis. Malonyl coenzyme A involves this same principle in fatty acid synthesis in the cells. Results
The progress the first year (1967-68) exceeded expectations. Nearly 40% of the students received A or high B grades. The students who had difficulty lacked preparation in the prerequisites. However, about 20% of the students who had average grades in general chemistry did exceptionally well; these students seemed quitewell prepared in principles of chemistry. Table 1. Comparing Scores in Biology and General Chemistry with the Rank in the Present Course
Student group
Top 24
Middle 15
Bottom 12
Biology
3.1a
Ch~rnmt,rv
2.8
3.0 2.3
2.8 2.2
4 is A and 1 is D .
There was very little or no correlation (Table 1) between the grades received in this course and courses in biology. The top 24 students in this course averaged 3.1 (4 is A and 1 is D) in 10 or more quarter hours of biology. The bottom 12 averaged 2.8 in biology. There was some correlation (Table 1) between this course and the course in general chemistry. The top 24 students averaged 2.8 and the bottom 12 students averaged 2.2 in general chemistry; the middle 15 students averaged 2.3. Fifteen of the students in this class had a t least one quarter of organic chemistry. The average grade for students in this group was no better than the grades of students with no previous courses in organic chemistry. It seems most important to admit only students without previous study in organic chemistry. Therefore, the advisors were asked not to allow students with organic training to register for the course in 1968-69. This was done because many of the students without organic training used this as an excuse for not doing well. The year 1968-69 proved to be even more successful than 1967-68. The first class period of the second quarter (2 hr) was devoted to an examination covering the first quarter's work. The examination was similar to the final given a t the end of the first quarter; the students had been notified concerning the examination in advance. The average on this test was 92y0 for those who received an A a t the end of the second quarter. The remainder of the class averaged 76% on this test. Part I of the 1968 ACS Cooperative Biochemistry Examination was given to the students who completed the course on schedule. This replaced the final examination. The students were NOT informed in advance concerning this examination. However, they did know that the final was to be multiple choice. Since the final examination is a 2-hr examination, we required the students to write all structural formulas and equations on separate sheets when the questions involved such information. They were allowed fifty minutes more than the allotted time for the standard test. This probably gave most students a chance to make a better score. 538
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Journal o f Chemicol Education
Table 2. Test Scores for the 1969 Class (Part I of the ACS Test)
Number of Students
---Raw Means S.D.
Score---
1968
Max.
Min.
%ile Rankb
43 43 35
24 36 24
between 8 5 ~ 9 0 between 90-95 just above 80
3 6 . 0 f 4.3 All 35 39.4 .. . Top 17 Bottom18 33.0 ... * Standard deviation.
' From average scores.
None of the 35 students (Table 2) ranked below the fiftieth percentile. The mean and the median scores were both near the ninetieth percentile. The upper 17 students ranked (Table 2) above the ninetieth percentile. The mean for the lower 18 students was just above the eightieth percentile. The computer analysis shows that the majority of students omitted questions NOT covered in the course. For example, since this is a course in human biochemistry, metabolism in plants was omit,ted. Only four students answered this question on the examination; two of these chose the correct answer. Two questions were answered correctly by all 35 students. Five other questions were answered correctly by 34 of the students. Summary and Conclusions
Students in life sciences with limited time for study would profit by an integrated organic-biochemistry course after satisfactorily completing a good course in principles of general chemistry. Our results indicate that students do learn elementary biochemistry by the organic approach. These students learn elementary principles of biochemistry by writing organic reactions occurring in the digestive tract and the cells of the human body. When energy foods are treated as organic compounds, there seems to be a stimulated interest in organic chemistry. A course of this type might be beneficial for students of education who are studying to be teachers in our elementary and high schools; this would give them a better idea as to how the body functions. Biology textbooks refer to DNA, RNA, Krebs' Cycle, etc., which have little meaning without some understanding of the chemical aspects. Understanding of the body functions is more important than ever before because advertisements concerning nutrition often lead to false ideas. It seems likely that a course of this type would open the way for a better understanding of the functions of chemistry in life processes; such a course should be open to all secondyear college students with a "C" average or better. This integrated course is an interesting approach t o the "introduction to organic chemistry." One reason the students learn biochemistry so efficiently is because they practice (repeatedly) specific types of organic structures and reactions which occur in our digestive tract and in our cells. The learning process becomes automatic. The structures and types of reactions are more limited in number than in a straight organic course. Acknowledgments
Thanks to Dr. Clifford Angerer, Physiology Department and to Dr. David Cornwell of this department for their suggestions in preparing this manuscript.
