William Jed Television Division of officeof lnstluctional Resources John A. Katzenellenbogen, Martha S. Okamoto. lain C. Paul.' ~iliiam H. ~ i r k l e , and Paul G. Schmidt School of Chemical Sciences University of lllinois Urbana, 61801
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The Chemistry of Life A second semester course on color videotapes for students in life sciences
Two main aspects of this course were: first, selection of subject matter appropriate for a second-semester course for freshmen with interests in biological science, and second, the course was to be built around a set of video tapes. In very early 1972, a decision was made in the Chemistry Department a t the University of Illinois to put its two-semester sequence in freshman chemistry for non-chemistry majors on color videotapes. The courses would he taught in the X-section format2 with a 15-25-min videotape being shown in the regular 50-min classroom period 4 times-a-week. Classes number between 2 5 3 0 students under the s u p e ~ s i o n of a graduate teaching assistant. While the first-semester course was quite general in content, the second-semester course was designed for students interested or majoring in the life science^.^ The present paper describes the content of the second-semester course which was entitled 'The Chemistry of Life,' the television and educational techniques that were used to put this course on color videotape, and a brief description of the organizational structure for making the videotapes, and of their use in the classroom. An evaluation of the X-section format is described by Enger, et al.4 When the project was undertaken there were two main aspects confronting us. The first involved the selection of subject matter appropriate for a second-semester course for freshmen with interests in the biological sciences. This course was to build on the more general first-semester course and the major topics deemed most suitahle were the basic concepts of molecular structure, chemical bonding, molecular interactions, thermodynamics, and kinetics to be presented in an organicbiochemical context. Secondly, this course was to be built around a set of color videotapes that ideally would each last about 15-25 min for use in the X-section format. The challenge in preparing these tapes involved the optimal utilization of the TV medium by stressing illustrative and dynamic material that could not readily he shown in the classroom. The two main aspects of the project will now he descrihed in detail.
capability for interaction with other molecules, and their tendenw to undergo certain fundamental reactions. Some of the discussions on energy, entropy, and free energy focus on nutrition, energy cycles in the metabolic process, and the forces that stabilize protein and nucleic acid structure. Kinetics and mechanism are developed to cover enzyme catalysis; the relationships between enzyme structure, substrate interaction, and catalysis are emphasized. Some of the topics covered in the course will now be descrihed in more detail under four sections: general introductory topics, the structures and means of interaction of oreanic com~oundsand hiomolecules, thermodynamics (energetics), -and kinetics and mechanism.
Selection of Course Content The main topics of the course are a description of structure and interactions in organic compounds and hiomolecules, an introduction to thermodynamics, and an introduction to kinetics. In order to develop these major topics, there is an introductory discussion of some of the properties of water, of ions, of acids and bases, and an essentially empirical description of bonding in carbon. As much as possible, theory and principles are introduced and developed into a unified body of descriptive chemistry and the material is presented on a descriptive level that is close to the student's experience so that it can be readily grasped by him or her. Theories and principles are invoked as tools to provide explanations, to allow correlations, and to permit predictions to he made. The topics in the course are discussed with special references to organic molecules and biological macromolecules. These aspects of organic molecules that are important in biological processes are stressed, such as their physical properties, shape,
In this section, an attempt is made t o help the student to understand the physical and chemical properties of a compound on the basis of its molecular and electronic structure. Structural isomers. stereoisomers. and conformation are introduced in the context of saturated hydrocarbons, and the relationship between conformational freedom and melting point is illustrated. The key reactions of hydrogenation and hydration for alkenes are descrihed and the unusual properties
General Introductory Topics
These include a description of the chemistry and physical properties of water, of the properties of ions, of the properties of acids and bases, and an introduction to bonding in carbon. The unique physical and chemical properties of water are described and related to hydrogen bonding and polarity, and the particular "fitness" of water to life on earth is stressed.s Dipole moments, electronegativity, polarizahility, and the covalent-ionic bond continuum are introduced. The nature of the forces in ionic crystals, and between ions and solvent molecules are descrihed with some mention of biological ion . transport. Weak and strong acids are compared, and the Henderson-Hasselbalch equation is developed to explain the nature of buffering. The position of carbon in the periodic table and its unique role in nature are analyzed. The atomic orbitals and hybrid orbitals of carbon are described empirically and the types of molecular orbitals found in carbon compounds are presented. Organic Compounds and Biomolecules
Address correspondence to this author. 2Haight, Jr., G. P., et a1.-preceding paper describing Chem I ni In addition to this second semester course designed far biological majors, an alternative second semester course was designed for engineering majors. However,this course was not taught in the X-section format, nor put on video tape. Enger, J., Toms-Wood,A,, and Cohn, K., following paper. Henderson, L. J., "The Fitness of the Environment," Macmillan Co., New York, 1913.
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of aromatic hydrocarbons are explained by resonance. Halogenated compounds are illustrated with reference to certain man-made chemicals that pose environmental hazards. The description of alcohols and ethers offers the opportunity to contrast physical properties due to the presence or absence of hvdroeen bondine. and chiralitv is introduced while descril;ing glucose. TGimportance bf sulfur compounds and amines in medicine is stressed. The mechanism of nucleophilic addition is analyzed in relation to the dipolar nature of the carbonyl group in aldehydes and ketones, while soaps, detergents, and membranes are introduced when carboxylic acids are discussed. Amides and esters are illustrated by drugs (aspirin, heroin, LSD), and the mechanistic aspects of ester hydrolysis are described. The various levels of structure-primary, secondary, tertiary, and quaternaq-are described for proteins and nucleic acids. The geometric nature of the peptide bond and its capacity to participate in hydrogen bonding to give structures such as the a-helix are stressed. A discussion of the variety of side chains and their weak interactions leads to a description of the tertiarv and auaternarv structures of a series of oroteins, and the physical a i d funrtiinal properties of proteinsare illustrated hv the abnormal hemoelobins that cause sickle cell anemia a n i the forces involved yn the enzyme-substrate interaction in hydrolytic enzymes. The importance of hydrogen bonding and steric complementarity in the double helical structure of DNA, and in nucleic acid replication is described. ~
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Adaptatlon of the Course Material to the N Format Once the decision to teach the course by way of color video tapes in the X-section format had been reached, it was trecessarv to make a number of decisions about the manner in whicl; the materiel would be presented on television. Certain technical limitations (lack of editing facilities, poor quality reproduction of l6mm film) were imposed on us, particularly at the heainninr of the ~roiect,by the available television equipment. It w& necessk prepare everything in advance and to arrange a specific day to put the production on tape. Past experience in the Chemistry Department assisted us in making a number of important decisions that proved critical to the acceptability of the tapes.2 The tapes would he quite short (i.e., 15-25 min, if possible). We strove to avoid the traditional lecturer-blackboard format by having the "television instructor" appear on the screen for times of only 1 5 2 0 s when introductom. transition. or concludine ".emnhasizine. . statements were being made. wehave always had two t e l c vision instructors--one male. one female. Alternation of their voices heightens interest when emphasis is necessary, or new topics are introduced. We have taken every effort to have the material, on the screen visually stimulating. We avoided long periods (>I5 s) with purely static scenes, and often topics were selected partly because they could be presented in a visually stimulating way. Topics such as detailed problem solving, long mathematical derivations, and the systematicsof organic nomenclature were de-emphasizedin the taped presentation, but were scheduled
Energetics
This series begins by introducingthe concepts of heat, work, and internal enerw both in relation to macroscopic and to simple molecular &stems. The law of conservation of energy leads to the concepts of a state property and enthalpy. Applications of the first law include calorimetry, heats of reaction, the evaluation of bond strengths, and concludes with a description of the chemical and energetic basis for nutrition. The question of spontaneity in both physical and chemical changes is used to introduce the second law of energetics, the concept of entropy, and its relationship to probability. The interplay between entropy and enthalpy (energy) leads to a discussion of free energy asan indicator of spontaneity. The energetic basis for chemical equilibrium is described and the equntions relating standard free energy change to the equilihrium constant me derived. This section concludes with some topics in bioenergetics: a description of the cell, the roles of ATP, sugars, and phosphate esters in storing chemical energy, and the origins of life. Finally, the complexity of hioloeical enerrv cvcles is illustrated hv an examination of the energetics invoived in the various stkps of the Krebs cycle. Kinetics and Mechanism
This series begins with basic definitions and principles: reaction rates, transition state, activation energy, and the lack of correlation between the magnitude of the free energy change for a reaction and the rate of the reaction. The effect of temnerature on reaction rates is examined in terms of the activation energy barrier. Reaction order, molecularity, and rate-determinine stem are discussed and the ex~ressionsfor first-order and skcond-order rate laws are deriied. The enereetic hasis for catalvsis is eiven end illustrated with heterogeneous and homogeneous catalytic processes. The section on biokinetics uses urease to illustrate the catalytic power of enzymes. The great structural and stereo specificity in enzymic catalytic action is demonstrated by carboxypeptidaseand fumarase. A detailed description of the structure and molecular mechanism of the action of lysozyme is given. Enzyme kinetics are introduced in a discussion of acetylcholinesterase, and Michaelis-Menten kinetics are derived from an essentially experimental basis. The effect of inhibitors is described, and the molecular basis for the action of the inhibitor, neostigrnine, used in the disease, myasthenia gravis, is outlined.
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Figure 1. An card illustrating the structures and bp's and mp's of the structural isomers, 2methylheptane and tetrarneihylbutane.
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Figure 2 This mlght nappen oltne second law olenergettcr did not apply. lldea ham a draw ng by Sts "berg, The hew Yorker. 1963.)
for live discussion by the teaching a s s i ~ t a n t s Whenever .~ possible, examples for demonstrations were chosen where striking color changes took place. ~.o e a r e don screen was resented Much of the material that a . using artist-prepared graphics. Some of these simply contained lettering on a differently colored background (for example, for structural formulas); others were fairly complex, multicolored drawinas depictina some chemical point (such as a sketch of a rockchasing a m a n uphill) (F&. 1i d 2). Generally, graphs rather than numerical data were used to illustragq&.itative comparisons; numerical data were given in the syllabus. Static illustrations were also provided by 35mm color slides and by color and by black and white tographs; this latter technique was used frequently to show pictures of chemical pioneers or, occasionally, famous experiments. The PLATO system6 developed at the University of Illinois provided another important means of conveying written material. The abilitv t o write. erase. and flash letters and numbers rapidly on the plasma panel of the PLATO system allowed an effective means of communieatine -simole . drawines. -. definitions, derivations, and worked examples. Even moderately complex animations such as drawings of gas expansions could be accomplished without difficulty by filming the image of the PLATO screen and using a television special effects generator to add color (Fig. 3).
Figure 3. Adding heat to an ideal gas system and watching the expansion using PLATO graphics.
Figure 4. Photograph of a molecular graphics sequence an the screen showing molecules of 2-methylheptane in the melting process. (Produced by the C o r n puler Systems Laboratory of the Medical School at Washington University in St. L o ~ i s . ~ l
More complex animations were effected in various ways. If the sequence was essentially two-dimensional (such as the passage of molecules over an enerw barrier), but the amount bf movement was too great for th&e of the PLATO system directly, a movie film could be produced using the PLATO system as an automatic animation generator. In cases where the material to be animated was threedimensional, or where specialized techniques were necessary, we collaborated with several groups from other institutions. In particular, we made black and white 16mm films of molecular graphics showing animated and complex molecular svstems with the aid of Dr. W. T. Wioke. then of Princeton Gniversity? and with Dr. C. David ~ a r r ;of the Computer Svstems Lahoratorv of the Medical School a t Washineton university in St. L&? Examples included pictures o r t h e supernosition of various substituted cvclobutanes to deter. . mine whether the structures represented lsomcri or not, and a fairly lengthy sequence illustratinr! the rneltine behavior of the two ~8iso&er~2,2,3,3-tetramethylbutane and l-methylheptane (Fig. 4). We were also fortunate enough to have the assistance of Dr. A. C. Wahl and Dr. Tim Janis from Argonne National Laboratorysin making a series of color 16mm films showing the interactions of various types of simple atomic orbitals to form both bonding and antibonding molecular orbitals (Fig. 5). As an additional aid in the dramatization of certain chemical processes that involve particularly dynamic interactions, we used the medium of the dance.1° For this purpose, a number of graduate students and friends would be recruited, dressed in color-coded T-shirts, and instructed in the approAnimations were done on the PLATO system of the Computerbased Education Research Laboratory of the University of Illinois, Urhana, Illinois 61801. W. T. Wipke, molecular graphics system at Princeton University. Dr. Wipke's present address is Department of Chemistry, University of California at Santa Cruz, Santa Cruz, California 95064. We thank Dr. Wipke for his assistance in this project. 8 C. D. Barry of the Computer Systems Laboratory, Washington University Medical School, St. Louis, Missouri, 63110. We thank Dr. Barry and his colleagues for their cooperation,enthusiasm,and participation in this project. Dr. T. Janis and A. C. Wahl of the Chemistry Division, Argonne National Laboratory, Argonne, Ill. 60439. Some aspects of the special color graphics system and of similar films are described by Wahl, A. D., and Blukis, U., J. CHEM. EDUC., 45,787 (1968).We thank Dr. Janis and Dr. Wahl for their generous assistance and cooperation in this project. The idea of "dancing" chemical and biochemical interactions m e to us after we saw the film "Protein Primer: Protein Synthesis," produced by the Senses Bureau (Dr. Kent Wilson) and now distributed by Harper and Row, Publishers, Inc.
Figure 5. The combination of two 1s orbitals to form a bonding molecular orbital. Filmed at Argonne National Laboratory.
Volume 55, Number 4, ADrii 1978 / 227
Figure 8. A rhinoceros is a resonance hybrid between a unicorn and a dragon.
Figure 6. A protein dance. The dancers wore different colored sweatshirtsto indicate backbone, polar side chain, non-polar side chain, or water molecule. priate motions. The dances that involved 20-30 people were filmed indoors in the TV studio, hut sequences that involved 50-60 participants were shot out-of-doors from a height of about 80 ft. The orocesses that were illustrated hv indoor dances included the action of ion carriers (a large person the inside dressed in a long hlack-"hydrophobic"-cloak, of which was blue "hydrophilic") in carrying ions (red) through membranes and the passage of gas molecules between two halves of a container with and without the intervention of Maxwell's demon. Out-of-doors, we demonstrated several aspects of protein structure with the backbone and polar and non-polar side chains of the protein appropriately colored
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Visual excerpts from commercially made films were included. where suitable ones were available and where we could obtain permission for their use." Among the examples used were some animated seauences from two excellent films on protein and nucleic acid s t r u ~ t u r e , 'and ~ a vivid sequence showing the demolition of a large apartment complex (Fig. 7).13
Among demonstrations that were filmed locally were the sphericalappearance of oil drops in water and their coalescence to illustrate hydrophobic bonding and the addition of catalase to some hlood. with resultant "hlood boilinr" to demonstrate enzyme catalysis.
Wherever possible, we attempted to show examples (such as polyunsaturated fats, drugs, and nutrition) of the importance of chemistrv in evervdav " " life. At other times, we have constructed a humorous scenario to attemot to illustrate some soecific noint. The aim was to add some humor to the teaching of c h & k d ideas and also to huild an analom which mieht strike a resoonsive chord with the student rather than a mere definition:~robability theory was introduced hv means of a eambline scene with the probabilities of thr&ing the various numb& between 2 and voune- man, armed with 12 using two dice being calculated. A . the elements of theory, and a calculator (and an attractive companion) was able to outwit a gang of rough gamblers who did not have these advantages. The analogy between a man ascending a hill by various means (climbing, driving, etc.) and using altitude &a state property, was drawn to a chemical process taking place between the initial and final states and usine enerev ".and entronv as state processes. Measures of a man's progress, such as shoe wear or gasoline consum~tion. . . would not he state orooerties in this context as they are dependent on the route &ken; they would be analogous to heat and work in chemical orocesses. Finallv. we enacted an analogy to explain resonance structures, which have no real existence, hut are used to describe the true structure of a molecule such as benzene. The analogy involves the story of a knight in medieval times who, upon returning from a journey in Africa, tried to describe to unbelieving listeners his encounter with a real rhinoceros hy using the unreal but, to hi listeners, familiar pictures of a dragon and a unicorn (Fig. 8).14 Occasionallv. we would huild uo the oersonalitv of one of , add the early che>cal pioneers, such & count ~ u m f o r band a historical vignette on his life and work. We also tried to convey some of the personality of the various television instructors, for example by showing one several times on amotorrvrle. ----, ---In summary, the concepts that guided us in adapting the material for the TV format, were to find the best match he&.
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" Permission to use video excerpts from commercial 16 mm films
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was usuallv bv the oublisher or distributor. However. there . .manted . ~
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were exceptions, most notably a major scientific pubiisher. McGraw-Hill Book Cmnpany, proved most uncooperative m g ~ n g
us permissiun t
