A Biochemistry Course 'for High-Ability Secondary Students Marie Sherman 7602 Weil Ave., St. Louis, MO 63119 This article describes a one-semester secondarv-level biochemistry course which I have taught for 14 yearsat ~ r s u l i n e Academy in St. Louis, Missouri. This course is designed for seniors of high academic ability who have completed courses in biology, chemistry (CHEMStudy level) and, in most cases, physical science. The purpose of this course is threefold: (1) To acquaint the students with the basic principles of bio-
chemistry, in preparation for college courses. ehallenee " the student who is seriouslv considerine -a science-related career. (3) To serve as a springboard for Science Fair projects. Students have won many college scholarship,trips, and prizes as a result of their projects. (2) To -
Ursuline Academv. .. with an enrollment of 600, is a private college-prep high school fur girls. For many years a l m h the onlv scientific field which attracted its maduates was nursing. ~h;sical science, biology, and chemist6 were the only science courses which were available. In 1968 a decision was made t o offer a fourth year of science: a one-semester "Honors" course in biochemistry, followed by a one-semester course in human physiology. his has proven to be an exceptionally popular and successful combination. (In addition, a one-year course in college credit physiology is now offered.) The number of biochemistry students has grown from 6 the first year to 29 (in two sections) this year. The text currently used for the biochemistry course is by Routh (I)and is accompanied by a programmed-learning text by Stephenson (2). Fourteen offprints from Scientific ~ m e r i c a nare also used for supplemental reading and discussion. These readings cover such topics as cell biology, proteins, enzymes, DNA, ATP, viruses, fats, and winemaking. The main disadvantage of the offprints is that some of the older ones are now out of print. It is an excellent experience for the students to be req2red to read and understand these articles. At the end of the semester, they are usually surprised by their vastly expanded vocabulary and by the ease with which they can attack any Scientific American article. The syllabus for the semester includes the topics listed below, plus appropriate experiments (Table 1): Cell Biochemistry Proteins Nucleic Acids Biochemistry of Genetics Enzymes
Carbohydrates Lipids Biochemical Energy Metabolism of Lipids and Carbohydrates
T h e Carbohydrate unit, for example, has the following plan: Lecture Topics Experiments Polarimetry of Sugars Molecular Structure and Optical Activity Classification of Sugars Chemical Tests for Sugars Reactions of Carbohydrates Disaccharides Polysaccharides Quantitative Determination of Sugars in Fruit Juices Approximate time required: 2-2% weeks Tests given after each unit always include some items related to the experiments, in addition to the usual items concerning the lecture material. Much emphasis is placed on the correlition of lah work with lecture informaGon and concepts. 902
Journal of Chemical Education
Table 1. Llsl ol Blochemistry Experlmenls (1) Amino Acid Chromatographya Biuret Analysis of Proteina (3) Chemical Reactions of Proleins' (4) Chemical Tests for Sugars*4 (5) Chemistry of FermentatiofV (4.5) (2)
161 DNA Analvsis (71 DhA hydro ysis and Chromatography (81 Exper~mentswlth Rennin*
(9) Exnactm of Fat horn Jmk Foods*' (lo) Extraction of Protein hom Dry Milk. (11) Introduction to SpectrophotometryaL 1121 . . iodine Number of Fatsa
(13) Kmet cs of Yeast invertase* I141 Paper Cnromatogapny 01 Svgars (151 Poiar~metryol Sugars hrmonslrations and AnaiyseJ.' (16) Radioactive Tracers in Plantsb (17) Saponification of Fatsa (18) Ouantiitive hrtermination of Sugars in Fruit Juicesa (19) Studies of Mushrwm Tyrosinasec(g) 120) Study of Excretion of Salicyiate in Urineo (21) Vitamin C (Ascorbic Acid)Analysiso .Exprimen!$
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Tabla 2. List of Blochemidry Laboratory Manuals (1) Arow. L. E., "lntroducthn tolabaatoryChemistry."C.V. Masby Campany. S t Louis. MO. 1976. ~-~~~
(2) b u m . S. J., Bowen. W. R. and Fwner. S. R.. "Laboratory Exercises in OF ganic and Biological Chemistry." 2nd ed.. Macmillan Publishing Co.. New Ywk. NY. 1981. (31 . . Clark. J. M., and Swber, R. L. "Expwimnlai Biachemisby." W. H. Freeman and Ca.. San Francisco. CA. 1977. (4) D'Auria. J. M., Gilchrist, A. 8. Johnstone. J. J., "Chemisby and the Environment." Philsdebhia. ~- W. G. Saunden. ~ ~ . . PA.. 1973. . ~ (5) Ddti. L. B. and Orten.J. M.. "Labwatwy Experiments in Biochemistry;' C. V. Masby Campany, St. Louis. MO. 1971. (6) HorwiQ. W.,,(Edifor)."Oflicial Methods of Analysis of the Associatim of OHicial AnalVtlcal Chemists." 13th ed., AOAC. P.O. Box 540, Benjamin Franklin Station. Washington. DC 20044. 1980. (7) Keleti. G., and Lederer, W. H., "Handbaok of M i a a r s m o d s fcf Um Biogicai ScienCeS." ~~~. Van Nostrand. New York.. NY.. 1974. (8) Rofi. J I.. 'Experiments in Ovpn8c and Biochemistry." W. B. Saunders. Phdadelphia, PA. 1971. (9) Strong, F M. an0 Kocn. G. H.. "Biochemistry Laooratory Manual." Wm. H. Brown, Dubuque. IA. 1974. ~~
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Students are also encouraged t o follow their interests into further investigations, such as: (1) Paper chromatographyof sugars (2) Inversion of sucrose by invertase (process followed with the
polarimeter) (3) The "silver mirror" experiment (glucosereacts with Tollen's Reagent to produce a silvered test tube or flask) Since I have not found any biochemistry laboratory manual which is completely suitable for the secondary level, I select experiments from a large collection of college lab manuals (Table 2). Some of the older manuals are more practical for a high school course, hecause they have less emphasis on expensive instrumentation and radioactive tracers.
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Table 3. Fleld Trip Locations (1) Bardenheier's Winery (2) Cytogenetics Laboratoty, local hospital (3) Hwpitai Clinical Labwatories (4) Kidney Dialysis Unlt. local hospital (5) Mallinckrodt Chemical Company 161 Mailinckrodt Institute of Radioiw~ .. (7) Med cal Scnwl Lvxarles (s) Manranto Company ( 9 ) Natlona Center faBug Anaiysis (to) Police Crime Laboratories (1 1) Rehabilitation Hospitals (12) St. Louis Medical Society's Museum of Medical History and Quackery (13) St. Louis University Medlcal Schwi 1141 , . Universitv of Missowi-Columbia Research Reactor (151 Unwersoty ol Msso~rt-StLouis Research Laooratwies (16) Wash "@on Un-uersty Remarch Labaaor es
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hazards: flammable solvents, caustic reagents, carcinogenic materials, or radioactive compounds. Complete instructions on the dawers of such substances, as well as safetv precautions and first-a:d procedures are emphasized before and during the experiments. The fume hood is constantly utilized for dangerous solvents; safety goggles, plastic aprons, and gloves are always used; rules for handling radioactive tracers are scrupulously followed. One of mv favorite experiments is the making of a gallon of wine ( 4 ) . W; usually seiup the fermentation durinithe first week of October, and the wine is then ready by the Christmas holidays. Needless to say, I obtain written permission from the parents; it is clearly understood that there will he no tastkg or drinking of the wine on school premises, and that only chemical tests will be performed on the wine at school. After the initial fermentation period, the students take their gallon jugs home tocomplete the process. In December they hrine small samoles 1-20 ml.) back to school for final analvsis f i ¢ alcoiol &d acidity which is related to the stud; of enzymes, carbohydrates, anaerobic glycolysis, and the history of Pasteur and Biichner. In order to learn about the commercial nroduction of wine. we also visit a local winery during0ctohe; to view their large-scale operations. Monthly field trips of about 2 h duration have been an integral feature of the biochemistry and physiology courses, since they were first introduced at Ursuline Academy. The St. Louis area is unusually rich in community scientific resources and in scientists who are willing to share their laboratories, research, and know-how with students and teachers. The administration and faculty of our school have cooperated whole-heartedly with our efforts to use these local r&ources for the benefit of our science students. Many of our alumnae have attributed their career choices to the "learning experiences" of our field trips. Table 3 lists some of the places we have visited during the past 14 years. Since the biochemistry course was started in 1969, 191 students have been enrolled. The Alumnae Office keeps close track of our graduates, and we have found that at least 150 of these students either have degrees in science or are still in college. The list includes large numbers of medical technologists, physical and occupational therapists, nurses, dietitians, pharmacists, a growing number of engineers and computer scientists, several PhD's in chemistry and physiology, a group in medical and dental school, and a practicing dentist. The feedback from the alumnae has been 100%positive, and they frequently visit the school to speak to the present classes and eive them information and encouragement about career OPportunities. It is mv h o ~ that e this descri~tionof our course will intereat other teachers in starting s i m i i biochemistry courses in their own schools.
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The expenses of setting up the course fell into two categories: (a) instrumentation (a Spectronic 20, a polarimeter (3), a pH meter, and a small centrifuge) and (b) chemicals such as amino acid samples and specialized reagents and solvents. Many college hiochemiswy texts have also been purchased for reference purposes. Recently, two additional Spectronic 20'9 have been donated to us, making more hands-on spectrophotometry labs possible. Since our school has onerated on a flexible "modular" schedule, I have been able tb plan four class meetings per week of 50 min each. and a loneer lab ~eriodlusuallv 1Vr2 .- h). once a week, in orde; to cope G t h the iengthy'procehres necessary for hiochemistw exoeriments. The experiments'have varied somewhat each year. Table 1eives an alohabetical listine of the ones we have used over t& past 14 ;ears; the ones used this year have been designated. I have also "invented" exoeriments on the sour of the moment. Several years ago, whenwe were titrating the amount of ascorhic acid in fruit juices, one student remarked that she was taking 1000 mg of ascorbic acid daily on the advice of her ohwician. We discussed the ooasihilitv that much of this dose k&eliminated through her didneys. The next day the student brought in a s~ecimenof her morning urine. which we comparei with a specimen from a student who took no ascorbic acid. While the analysis may have had a good many scientific flaws, it did show a considerable amount of an ascorhic acidlike substance in the urine of the "dosed" student, as compared with that of the "control" student. The experiment, "Extraction of Fat From Junk Foods" evolved in a similar manner. Each student brought her choice of "junk," preferably some dry, oily type of snack such as potato chips. The fat was extracted with 50:50 methanol: chloroform (good ventilation and plastic gloves are a MUST!).Percentages of fat in the snacks were found to he from 10to 26%. The student could then make a rough estimate of the total Calories (kilocalories) in the sample, by assuming that the remainder of the sample was either carbohydrate or protein. Some of the snacks were found to have approximately 1000 Calories per 8-ounce package--a rather sobering fact for anyone who wants to control hisher weight. Experiments such as the one described above can present
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Literature Cited (1) Rauth, J. I,"tntmduetionto Biocbemiat.yO.W.B. Savndem Company,Philadelphh PA, 1978. (2) Stcphenaon,W . K.,"CoacepBia Bioebcmi.tryo( 2nd ed., John Wiey and Sons. Nea York.NY. 1978. (3) "Polanmstcstc in CoUw ChemistnCo-.'. Instmsnte forReasareh and IndusW. Cheltenham, PA 18012,lWS. (4) Horn. D. E.. J. CHeM. EDUC.,64,376(19R). (5) McClure, D.W.,J. CHEW EDUC,63.70 (19761. (0) Friedman. M.E.,and Damn,H. H.,J. CHM EDUC.,54,256 (1977).
Volume 61 Number 10 October 1984
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