Fostering Curiosity-Driven Learning through Interactive Multimedia Representations of Biological Molecules Abby L. Parrill and Jacquelyn Gervay* Department of Chemistry, The University of Arizona, Tucson, AZ 85721 molecular attractions that would stabilize the various Recently we initiated a program in chemical educastructures. tion directed toward developing discovery-based learnThe movies were favorably received in class and ing methods in organic chemistry. As part of this promany students asked that they be given the opportunity gram we redesigned the lecture portion of our honors to “play” with the movies as the course continued. Thereorganic chemistry course. Beginning with a “big picture” fore, we have made the movies available to students on view we work backwards toward understanding fundathe World Wide Web (WWW). 2, 3 The use of the WWW mental concepts in order to explain an observed fact. By presenting students with a big-picture view and giving as a means of disseminating chemical information has them the freedom to break down the scientific observabeen rising exponentially (1–4). It is an appropriate fotion into component parts of familiar principles, we help rum for our movies because it allows interactive viewthem to discover whatever new information they require ing of 3-D structures and all University of Arizona stuto understand the observation. Often new information dents have free access to it from designated computer is required to fully understand the observation, so labs on campus. Additionally, hyperlinks allows students hypotheses are formulated and tested, and the scientific to easily find additional information in their weak arprocess continues. In this manner students take an eas, while skimming through or skipping familiar topactive role in their learning. ics. To supplement the lecture, three series of big-picture QuickTime movies were developed and presented in class during the first two weeks of the course.1 Topics dealing with the structures of proteins, DNA, and porphyrins were chosen because many students have heard of these biological molecules. When polled, most of the students knew that DNA formed a double helix, but no one knew why. Everyone knew that chlorophyll is green and oxygenated blood is red, yet they were surprised to see their structural similarity. They began to wonder how slight structural differences could give rise to markedly different colors. The fact that proteins can have different shapes depending on their amino acid content also sparked curiosity. The students were given the opportunity to take a closer look at the component parts of the biological molecule using interactive multimedia representations. The first movies in the DNA series show the polymer rotating about an axis to illustrate the double helix from all angles (Fig. 1). Subsequently, a portion of the DNA is extracted from the big picture (Fig. 2) and isolated base pairs are pulled apart, swapped with different bases, and then put back together. The viewer Figure 1. Initial frame of the movie showing the DNA double heis encouraged to look at the chemical structures and to lix. consider what makes one combination of bases more likely than another. The next movie shows two different perspectives of one paired base rotating about its bond to the DNA backbone, suggesting that consideration of intermolecular attractions may explain why bases consistently pair in the same relative orientation. The porphyrin series shows the change in geometry of the heme portion of hemoglobin when oxygen binds to the iron center (Figs. 3 and 4). Two movies separately show rotating heme molecules with and without oxygen ligands. This series encourages consideration of the effect of bonding and hybridization on chemical structure. The third series involves protein secondary structure, illustrating left- and right-handed alpha helices, an antiparallel beta sheet (Fig. 5), and conversion of an antiparallel beta sheet to a parallel beta sheet. Descriptions are given of the differences between left- and rightFigure 2. Initial frame of a subsequent movie in the DNA series handed helices, and the viewer is asked to look for interwhich shows a close-up of base pairing.
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Figure 3. Heme with no oxygen bound. Top: View of porphyrin. Bottom: Porphyrin rotated 90° to show iron out of the porphyrin plane.
Figure 4. Heme with oxygen bound. Top: View of porphyrin. Bottom: Porphyrin rotated 90° to show iron in same plane as porphyrin.
Methods and Implementation The basic explanations were implemented using the HyperText Markup Language (HTML) with links to the short movie clips in QuickTime format. The HTML files were prepared using the “Text Only” option when saving the documents from Microsoft Word. QuickTime™ movies were prepared using Ball & Stick from Cherwell Scientific. Some of the files needed by Ball & Stick were generated using the spline option available in Babel (5). The movies are accessible to any web browser over WWW at http://mercury.aichem.arizona.edu/chem242. html by clicking on “Quicktime Movies”. However, for full effect a graphical browser such as Netscape2 or NCSA Mosaic3 is recommended rather than a text-based browser such as lynx. The graphical browser must have access to a QuickTime helper application such as FastPlayer4 for the Macintosh or Apple’s QuickTime for Windows.5 Conclusions A series of QuickTime movies have been developed and made available to students via the WWW. Viewed in sequence, the movies first show a “big picture” based upon crystallographic data, and then narrow in on the basic concepts needed to understand the scientific observation. In this manner the students engage in the scientific process to discover how basic chemical concepts such as bonding and structure can explain interesting structural properties of molecules. The movies supplement the principle goal of our teaching program, which is to involve students in their own learning by providing a curiosity-driven learning environment. Acknowledgments We are grateful to the National Science Foundation for partial support of this work and The University of Arizona for facilitating WWW access through the use of a DecStation 5000. Notes
Figure 5. Initial frame of the movie demonstrating the β-pleated sheet structure. 2. Access to WWW possible using Netscape, available by anonymous ftp from ftp.mcom.com. 3. Access to WWW possible using Mosaic, available by anonymous ftp from ftp.ncsa.uiuc.edu. 4. Available from http://www.bookstore.arizona.edu/WWW/ Netscape_helpers.html. 5. Available from http://coyote.csusm.edu/cwis/winworld/ viewer.html.
Literature Cited 1. Bachrach, S. M. J. Chem. Inf. Comput. Sci. 1995, 35, 431–441; Proceedings of the First Electronic Computational Chemistry Conference (CD-ROM version); Bachrach, S. M.; Boyd, D. B.; Gray, S. K.; Has, W.; Rzepa, R. S., Eds.; can be ordered from ARInternet; Landover, MD; http://www.ari.net/chemnet/eccc-order.html. 2. Proceedings of the 2nd Electronic Computational Chemistry Conference; Bachrach, S. M., Ed.; Theochem–J. Mol. Struct. 1996, 368, 1–255. 3. Electronic Conference on Trends in Organic Chemistry (ECTOC-1) ISBN 0 85404 899 5; Rzepa, H. S.; Goodman, J. M.; Leach, C., Eds.; CD-ROM; Royal Society of Chemistry Publications, 1995; http:// www.ch.ic.ac.uk/ectoc. 4. Proceedings of the First Electronic Glycoscience Conference; Hardy, B. J.; Wilson, I., Eds.; Glycoconjugate J. 1997, 14, in press. 5. Shah, A. V.; et al. Babel—A Molecular Structure Information Interchange Hub; in Computerized Chemical Data Standards: Databases, Data Interchange, and Information Systems, ASTM STP 1214; Lysakowski, R.; Gragg, C. E., Eds.; Philadelphia, 1994.
1. The course consists of three 1-hour lectures, a 1-hour discussion section, and a 4-hour laboratory every week.
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*Corresponding author.
