The Oriein of Life was the theme of an interdiscinlinarv course which included aspects of astronomy, biology, biochemistry, geology, and physics. I t was conceived as a dramatic and effective way t o induce liberal arts undergraduates to undertake an intellectuallv challenaine exnerience in the sciences. Following several years of in&itt&t preparations, the three-credit course was offered for the first time fall term 1976,under the title "Origin of Life: Molecular Evolution and Exobiology." Its major objectives were 1) to promote the study of science in terms of meaningful and 2)
3) 4) 5) 6)
intriguing subject matter to provide a substantial scientific-intellectualframework and experience in scientific reasoning to provide perspective on mankind's relation to the universe to indicate the methods, current research frontiers, and significance of contemporary research in the biological and physical sciences to consider the possibility and implications for the existence of extraterrestrial, intelligent societies to he suggestive of possible career directions
Twenty-five students enrolled in this first course which had sophomore standing as the only prerequisite. A separate seminar section for seven junior and senior science majors was also arraneed. Three sirategies characterized the teaching. The first was development of considerable chemical background by introducing fundamental principles as needed during the gradual unfolding of the molecular aspects of life. This was accomplished by using a modified Personalized System of Instruction, PSI ( I ) , for the efficient transmittal of necessary technical information t o students with markedly different scientific and mathematical backgrounds. The second was to present the material in various ways so that each student encountered his own preferred learning style with subsequent reinforcement; thus, extensive use was made of films, slides, and videotapes. The third was to require that the students not only assimiiate new knowledge hutapply it in some useful or creative way as demonstrated by term papers or special projects. he course policy was early established that not only should scientific content he substantial but that any resources used must be scientifically impeccable. Texts, Articles, and PSI Aspects Since no single text was found auite aunronriate. two in .. . paperback editions were selected; these were "lntellig&t ~ i f e in the Universe" ( 2 )and "The Origins of Life" (3).The first, especially useful for astrophysicalind exohiological aspects, was updated by one of the authors, Carl Sagan, in the article "Life" from the "Encyclopaedia Britannica" (4). The course format and 1 2 PSI units corresponding t o t h e two texts plus several additional required readings were prepared, with some modification, according to established Keller procedures (5). Ways in which the course was individualized and kept current will become evident. The major topics covered and considered essential were astronomical origins of the elements, atomic and molecular structure, chemical bonding, formation of the solar system, Presented in part before the Division of ChemicalEducationat the Centennial National Meetinr.of the American Chemical Society, San Francisco, California, ~ u g u s1976. t
Table 1. PSI Untts and Course Syllabus Unit
Number
Title
I I1 iii IV V Vi
me Nature and Development of the Origin of Life Problem The Formation of the Solar System and the Earth's Atmosphere Early-Earth Geohistory and the Fossil Record Introduction to the Molecules of Life: Small Organic Molecules Prebiot,~Synlhesm and ma Earlest Lwng Systems R ~ V I and ~ WSelection of a Speelal Top c Evolnlon 01 Life on Eanh Extraterrestrial Life Bioenergetics and the First Law of Thermodynamics The Second Law and the Thermodynamic Definition of Life Supramolecular Organization: Principles of Self-Assembly Review and Course Evaluation
VII Vlii
ix X Xi XI1
Table 2.
Required Supplementary Readlngs
For Units
Title
Number
I, Vi. VII "Life" VI "Stars. Galaxies,and X XI Xi XI1
Universe" "Energy Transformations in Living Cells" "The Molecular Basis of Marphagenesis" "The Shategy of Man" "Whence"
Reference Number (4) 16)
(7)
(8 (9) (10)
early-earth geochemistry, prehiotic molecules and macromolecules. bioenergetics. suoramolecular organization, and the possibility of the existence of and communiration with extraterrestrial life. The titles of thr PSI units contained in the course syllabus, Tahle 1, indicate the sequence of presentation and integration of these topics. Headings suppl&enting the t e n t s m d keyed to the unit?* are shown in Table 2; these were uset'u1 to show contrasting viewpoints, update the texts, and indicate where scientific results had philosophical implications. Units VI and XI1 had major review purposes; in addition, Unit VI forced the selection of a special topic and XI1 included a course evaluation form. Two advanced undergraduates, one biology and one chemistry major, tutored the 12 self-paced Keller-style units, helped administer repeatable examinations, and shared in the laboratory and audiovisual aspects of the course; they were designated "Proctors" with one also sewing as Course Manaeer. Several classrooms were used with one eauinued . .. for " television viewing and another for laboratory demonstrations. Multinle rooms also favored simultaneous tutoring- and test in^ by the three-member staff. Supplementary Teaching Techniques The subject matter was of sufficient quantity and complexity that ways of enhancing the PSI format were considered necessary. The nine techniques used were videotaped lectures; live lectures; laboratory sessions; films; special projects or term papers; faculty-student conferences; newsletter, journal, and class reports; quantification; and cognitive mapping. Videotape Astronomy Lectures Three astronomy lectures were made availahle by a distinguished astronomer from nearby Cornell University (11). Volume 55, Number 8. August 1978 1 521
These were shown consecutively the first three weeks of the course and were entitled (I) "Origin of Life," (11) "Life in the Solar System: Problems of Detecting Life," and (111) "Life Beyond the Solar System." The accompanying color slides were simultaneously projected for convenience in viewing and to emphasize important details. An astronomical beginning to the course work seemed logical and proved effective. The stellar origins of the elements provided a logical transition between astronomy and introductory chemistry. Live Lectures
Six short lectures of about 20 minutes each covered chemical topics which students twicallv need heln with. and a fmal slide-lecture reviewed andgener&ized theterm's work. The titles were (1) "Atomic Structure, Molecules, and Chemical Bonding," (2) "Organic Chemistry," (3) "Energy and the First Law of Thermodynamics," (4) "Entropy and the Second Law of Thermodynamics," (5) "Self-Assembly and Supramolecular Organization," and ( 6 ) "Review and Integration." Films, model-building, and discussion followed the lectures. Laboratory Sessions
Two "laboratorv sessions" were held: the first was a model-building peiiod designed to develop the students' understanding of introductorv organic chemistrv. The isomerism, opticaiactivity, and uniquerole for life played by carbon were emphasized in terms of the structures of simple amino acids. Bd-and-stick model sets were provided to the students, and various biomolecules made from both space-filling and skeletal models were circulated. The second laboratory dealt with the formation of macromolecules and introduced their chemical, structural, and information-carrying functions in living systems. The polymerization and automated spinning into fibrous form of 6-10 Nylon were demonstrated by the elegantly simple Nylon-rope trick (12). This synthesis of a polyamide provided a natural entry to discussions of protein formation, the nature of enzymes, and the relationship of chain folding to biological activity. Films
A large selection of excellent, up-to-date films was and continues to he available through NASA, NSF, and private sources. The geological and astronomical aspects of the course were especially enhanced by the striking presentation of such spectacular phenomena as volcanic eruptions, supernovae, and black holes. "Mars, the Search Begins" was enthusiastically received; the simulated trip to Mars i t provided via the Mariner 9 space probe introduced the challenging field of nonterrestrial planetary studies. Several films effectively recreated natural events. Examples are the award-winning "This Land" from Shell Oil which retraced vividly, in color, the evolution of the North American continent and its life forms. "Birth and Death of a Star" from the American Physical Society simulated being dragged into a black hole with sufficiently convincing reality t o he enjoyable to a perceptive college audience. NASA's "Universe" is still one of the best films available. Both "The Ascent of Man" and "Nova" series are highly recommended for content and quality of production. Special Topics and Projects
The requirement for a special topic arose from the conviction that the scientific content of the course would thereby he absorbed faster, more meaningfully, and more permanently. I t was also expected that the students would gain confidence and experience in coping with technical problems. The search for a topic and/or project was itself an educational experience; the students either originated their own, subject to approval for scientific merit, or chose from a suggested list. T o minimize procrastination, the completion of Unit VI required in writing (1) a topic title, (2) a preliminary outline, and (3) three references. A bibliography and a substantial assortment of supplementary reference texts were supplied (13-24), and an extensive collection of scientific journals was readily available. 522 1 Journal of ChemicalEducation
Table 3.
Selected Special Topics
A)
Nanmajars (PSI) Section The Asnonomica1 Origin of the Elements Black Holes The Colonization of Space Cryptobiosis of Tardlgrades Evolution of DNA Remmbinant DNA Research Life Cvcles of Stars Tneoroe~an the Or gm ot the Unlverse Tne Sewch tor ExtralerreJlrlal Intel1 gencs 8) Sclence Ma ors Semmw Sect on Evolution of Cytochrome c Evolution and Photosynthesis Implications of Organic Constituents of Metmiter and CBT~O~BCBOUS Chondrites for Origin ot Life Studies Transition from Unicellular to Multicellular Organisms The Geology of Mars The Viking Biology Experiments Laboratory Projects: The Simulated Javian Atmosphere Thermal Polymerization of Polypeptides and Formation d ProteinoidMicros~heres
The titles of typical papers and projects are given in Table 3. Faculty-Student Conferences
These individual conferences were essential not only to assist in subiect selection. but most students needed heln in narrowing their tupics, outlining the significant aspects, and findinr! definitive literature sources. Questionnaires listine intere&, career plans, and course backgrounds were usefu! for ruidinr! the students. The oooortunitv orovided to know thestudents better and t o work coope~~t'ively on locating relevant new books and reports was especially worthwhile. Newsleiier, Journal, and Class Reports
Several methods were used to bring current developments, such as the launching of the two Viking spacecraft for Mars, into the ongoing course. One was to have periodic short reports by the students on their projects. Another was systematic journal coverage by a senior from the seminar section who with some assistance scanned the following journals: Astronomy, Chemical and Engineering News, Journal of Chemical Education, Mercury, Physics Today, Science, Scientific American, and Sky and Telescope. He developed three summary newsletters and. on several occasions. reviewed highlights for the class. He also helped compile a bibliography for current astronomical subiects suitable for term oaners: this included selected science fiction useful in provfding background, for example, on the colonization of space. Quantification
In designing the course, the question of how to treat the mathematical aspects of the subject matter was explored. I t was decided that problem sets involving detailed calculations would not be used and that for such nonscience maiors two mathematical goals were realistic. The first was the use of the exponential notation since the entities studied raneed from subatomic to galactic dimensions. The second was todevelop a common-sense order-of-magnitude appreciation of astronomical time scales, distances, and sizes. Typical quantities the students were expected to know were: the velocity of light, the ages of the Universe and the Earth; the remaining lifetime of our solar system, the estimated time interval for life to originate on Earth, the age of the oldest known fossils, the number of stars in the Milky Way and in the Universe, the distances from Earth to the sun and to our nearest neighboring star, Alpha Centauri, and the range of estimates for the number of possible extraterrestrial civilizations. Useful in this respect is an informative and striking collection of compari-
sons compiled by L. Berman (25); for example, the universal ranges of matter, time, and energy are tahulated as well as densities ranging from elementary particles to black holes. Cognitive Skill Profiles
The cognitive maps of over half the class were obtained on a volunteer basis. The skills inventory was provided by J. L. Hill of Oakland Communitv Colleze and allows comnuter analysis to provide the class profile f i r the teaching staff and individual urintouts for the students. The ournosea of this exercise were to provide information on the &ea of students registered for the course and t o increase their awareness of how they best learned. The overall profile showed highly esthetic, markedly individualistic students; as would be expected, fewer were strong in logical reasoning that would characterize science major$. Semlnar Session The science majors' seminar met jointly with the nonmajors' section for guest lectures, film viewings, and the subsequent discussions. In addition, the majors participated in one-hour weekly seminars which were based upon a more advanced text (25), adopted a research viewpoint, and required extensive journal readings which assumed appreciable scientific background and familiarity with modern laboratory procedures. A high degree of independence was expected in doing term papers and projects (see Table 3). In addition, t o student seminar presentations the required coursework included either two take-home examinations and a term paper, or two short papers plus a final slide-lecture which was taped upon presentation to the PSI section. As a special emphasis the second seminar session followed closely the results being returned by the two Viking spacecraft as they searched for life on Mars and photographed its geological features (see figure). Examlnations Mastery of Units I-XI was demonstrated by passing quizzes given in the Keller mode, i.e., on-the-spot or fast turnaround time for grading and unlimited retakes. A final examination consisting of five essay and 20 multiple-choice questions and covering d 12 units was required. The option of an early final was available upon completion of all units. Answers to some of the discussion questions were illuminating. Considerable pessimism was expressed concerning the survival probabilities of terrestrial and possible extraterrestrial technical civilizations. This was in spite of the fact that the general tone of the readings was optimistic and suggested that although serious problems existed, given human ingenuity, none seemed insurmountable. Another set of thouehtful answers arose in resnonse to the question of how, in thelight of genetic engineerin~possibilities available (for example, via recombinant DNA), given the choice, they would aim or direct human evolution. The almost unanimous resnonse was to "leave it alone.'' T o the extent that any change was acceptable, it was to minimize war-promoting tendencies. Course Evaluatlon Upon completion of the original course, written evaluations were collected. I t had been stressed that the course was new and that we were especially receptive to suggestions for possible improvements. There was enthusiastic response that the course be given again. As many as possible of various constructive suggestions were incorporated into the second offering of the course (Spring 1977). The chemistry content was annarentlv too concentrated in the earlv weeks. so this was re&stribu&d somewhat but not decreased or diluted. Additional modifications were the introduction of euest sneakers on UFO's and technical writing and the use oran adiitional text. "The Galactic Club" (27). here had also been a maj'ority feeling that at least one daytime class period, to supplement two evening ones, should
CDllectlon of uitraviole+sllieldedMartian sail sample from under rock by Viking 2 Lander arm. Right photo is afler rockpush and soil removal. (Photo, cowtesy of NASA.)
he held with more lectures. This was somewhat atwical for .. Keller-style programs which in many cases totally eliminate lectures and dns* meetinm or find them poorly attended. Such a class period was subsequently incorporated. Analysis of questionnaires and discussions with the students support the interpretation that they enjoyed not having to-compete against their classmates for grades but wished to maintain the sense of collegiality that comes from class gatherings in either lectures or seminars.
-
Gradlna The grades in Keller-style courses are known to run higher than comparable lecture-format ones (5). This has been justified on the basis of demonstrated mastery of the material. No analoeous courses were available for comnarison. but that grades were objectively earned was e s t a b ~ ~ h eb;d the followine noint svstem totaline 1.000 noints: twelve PSI units (50 eac6,600 point maximum); films; lectures, and laboratory sessions (5 each. limit 50): reauired final examination (150): . . term pager or laborator; project (200). Conclusions Experience with the course led to the following conclusions: (1) the origin(s) of life is(are) an effective way for both majors and non-majors to study science and for faculty t o broaden their scope. (2) The use of techniques other than live lectures is particularly appropriate to the subject matter. (3) The PSI procedure is one way of teaching an interdisciplinary science course which seemed esneciallv useful with students of mixed background. Costs can he kept modest by using a wide variety of hirh-oualitv. low-rental. and no-cost NASA and NSF films. ~ e l & i s i o nishelpful but'not essential. A more traditional teachine format could be used as. for examnle. the course on "The ~nierfaceBetween the ~ i v i n and g thi~&nlivingw(26). (4) A large amount of complex chemistry can be taught if made meaningful by the timely coincidence of good science and historical drama exemplified by interplanetary exploration and the search for extraterrestrial life. We recommend a course on the origin - of life as a challenging .. adventure in science. Acknowledgment We eratefullv acknowledee the sunnort bv Ithaca Colleee. of the center ftl; Individual land lnte;discipli&y Studies, Fh= Denartment of Chemistrv. and the excellent technical assistance of the lnstruction; kesources Center of the School of Communications. We are also indebted for the use of audioVolume 55, Number 8, August 1978 1 529
visual materials t o Cornell University's Science,Technology and Sorietv Pnmam and Prof. C. Saean. and to the National ~ e r o n a u t i i san: Space Administration.' Literature Clted I11 Kel1cr.P. S., J. Appl Behouior Analysk, 1.78 (1968). (21 Shklovakii, I. S.. and Swan, C.. "Intelligent Lifa in the Univeme." Ho1dsn.D~. 8an Franeiam, 1966. (31 Orgel, L. E.. "The Wiginsof Life, MolaeulunndNatvralSsl~ion,"John Wilay and Son%New York, 1973. (4) Sagan, C.. "EncyelopaediaBriDlonica."Vol. 10, Willism .ndHalanBsnton.Chimgo. 1971. pp. 893.911, (51 "PSI by PSI: A Workshop on the P a w n a l l Syatsm of I~utruuion.'B. A. G m n , Jr., Center for Personalid lnstructiin. Wsrhinglm, D. C., 1 9 7 6 . C o a d u d by DT. ~~~~
~~~~~-~
(61 Sandage, A., ~ e r e u r y 3.18 , 119741. (71 Lehninger, A. L.. "Biochemistry: Second Edition. Worth P v h k h n L ~ nc. N w York,
"" 7.Q ". ., .W E ,r... "
(8) Ref. 17) pp. 1011-1014. I91 Gm~teitein,C.,"TheStrate~~ofLifr:See~dEdltion, W. H. FremtanlodCompany. Ssn F~anciaeo,1974,pp. 16&166. 110) "Whence," Sir Bernard Lovell. abatreeted hom Praaidsntial addre88 to t h . B l i t i h Astronomical Assmiation. New York Times Co., 1975, p. 21. series delivered under the auspieu of Cornell Uoiveraity. 111) Sagan, C.. a thrc~~leeture Program on Science, T e c h n o l ~and , Saeiety. 1972.
524 1 Journal o f Chemical Education
(12) Morgan, P. W., and Kwdek, S.L., J. CHEM.EDUC., a8.182 (19591. 113) Ksnyon. D. H..and Steinman, G., GGBiihemicaI P~edutiiifim." MMGGG~.H'~I, NN
.".",.""".
b . "
,*"a
I141 Oparin, A. I.. "The Origin of Life oo Earth."Aurdemie Pmu. Ioe.. New York. 1957. 115) Wiison,E.O.,Eianer,T.,Rrig8,W.R., Diekerson,R. E..O'Bricn.R.Suman, M...nd Bogga. W. E., "Life on Earth." Sinauer Publihera. Stamford. Coan.. 197% (16) Diekemn.R. E.,andGsis. I.."The S t r m t d and AUianofPmtsii."HarprandRrm, NcaYork, 1969. I171 Fox, S. W., and Dose. R, "Molsukr EMlvtioa and the Oliginof Lisa," W. H. Tmmnn. San Flaneiaeo, 1972. 118) DwhoR. M. 0.. "AUaa ofPmtam Saquenes d s t r u e t u r a . Vol 6: Nation4 B i o m d i d Roaeareh Foundation, Georpstosto Uniwraity MediurlCenter, Waahinptonpto, D. C.,
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(19) Calvin, M., "ChemiealEvolution."OxfordUniwrsityP-,New York, 1%). (20) Price. C. C.. (Editor), '"Synthed8 of Life: BsnchmukPapus inOrganieChemistn,, Dowden, Hutchinaon snd Rma. Lnc., Shoudaburg, Pa., l9T4. 121) Buret, R.. and Ponnamperuma, C., 1Editoral;'ChemiealEvolution andthe O & i i o f Life." North Holland American Elsevier. 1971. (221 Hartman, W. K., end Rope., O.:'The New Mars: National Amnauties and S p m Adminiatration, U.S. Government Printing Offlee. W.ahiagtoton, D. C.. 1974. 123) Sullivan, W.. 'Dontinen* in Motion, Th. N w Earth Dsbste." MeDraw-Hill,N s r Ymk,
