Laboratory practical work as a technological process

Biochemical Education ELSEVIER

Biochemical Education 26 (1998) 281-285

Laboratory practical work as a technological process Augusto Pich-Otero, Sara Molina-Ortiz, Laura Delaplace, Oscar Castellani, Daniela Hozbor, Delia Sorgentini, Anl'bal Lodeiro Area de Quhnica BiohJgica y Biologia Moleculal: Facultad de Ciencias Exucla.s. U, iverskhul Nacicmal de La Plata. La Plata. AI74enthut

Abstract

Laboratory practical work is commonly intercalated with theoretical and seminar classes in packages that cover single units of a given course program. Emphasis is put in to illustrate important theoretical concepts and in to improve students" laboratory handling skills. Wc observed that this inw~lvcs serious disadvantages, namely (i) students lack an integrated view of the subjects, (ii) time constraints for each experimental session preclude students to become familiar with most of the techniques and approaches, Off) how to manipulate laboratory equipment become more important than the objectives and rational explanation of results, (iv) work planning and evaluation of reproducibility of methods are not considered, (v) elaboration and communication of results are not encouraged. To overcome these limitations we developed a new schedule were students get problem-based learning of theoretical concepts during the first half of the course and plan and execute a laboratory project during the second half. The project is performed within one of three main areas: purification, enzyme kinetics or metabolism~molecular genetics, with/]-galactosidase as model system. By inducing a more positive attitude in the students towards the practical laboratory work, this schcdulc allowed us to awfid the mentioned disadvantages while keeping the traditional practical laboratory work objectives met. © 1998 IUBMB. Published by Elsevier Science Ltd. All rights reserved.

1. Introduction

Traditionally, practical laboratory work has been a valuable method for demonstrating to students some of the concepts dealt with in lectures. In such laboratory classes, students are asked to follow a number of established recipes and protocols in order to attain a predetermined objective. Through the correct application of techniques, the experimental data obtained should fit with the predicted results and this is the main objective of each experimental session. The experimental observations are then used to revisit the theoretical concepts, from a point of view that now provides new insights based on real world situations. In addition, it is thought that this kind of organization of the course teaches students about the use of experimental methods and gives them the opportunity of improving their laboratory skills. The rapid global improvement and increasing acccssibility of technology requires that universities should produce independent and self-critical graduates who should be able to develop, carry out and control industrial processes by themselves, and who can take advantage of all available tools. In developing countries such as

Argentina, it is essential that new professionals arc able to understand and rapidly adapt to new technologies as they arise, as well as developing technologies by themselves as required for specific problems. Thcrefi)re, they should be able to learn.[or t h e m s e l v e s how to develop and implement completely new processes, and participate in close interactions with other professionals inside and outside the country and/or the company. The development of these kinds of skills are not addressed by traditional lecture/laboratory teaching programmes, thus it is left to the future professionals to acquire these skills themselves. In fact, these abilities are not very well acquired from textbooks or lectures; instead, they involve a very important element of reasoning and expertise, and the development of critical skills that only constant and focused practice can help to achieve. The authors are engaged in teaching biological chemistry to undergraduates in their fourth year of pharmacy training at the Faculty of Exact Sciences, National University of La Plata, Argentina. Since 1996 we have been setting up a new teaching strategy to get the students involved in practical laboratory work as a technological process, with the aim of providing adequate stimuli to develop the

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above-mentioned skills, in this way, laboratory work has been converted from "one more step in the course" to a major challenge that the students take responsibility for. Therefore, the responsibility for the way in which experimental work is conducted is shifted from the instructors to the students, and this constitutes the main motivation to carry out enough practical work (with mind and hands) to adequately develop the above-mentioned reasoning, expertise and critical skills.

2. Previous history of our laboratory practical work: W h y did we decide to make a change?

Up to 1996 we taught a traditional biological chemistry course. For each subject the students had lecture sessions complemented by problem-solving classes or seminars, followed by practical laboratory work that was done in the traditional way. The course was divided into four modules by subject (i.e. Structure and purification of macromoleculcs, Enzyme kinetics, Metabolism, and Molecular genctics), and each subject contained a complete set of lectures, seminars and lab work. Consequently, each modulc was essentially autonomous, and provided little incentive for the students to try to integrate the different subjects as needed in the real world (for example, enzymes are macromolecules that can be purified, which might have function in metabolism, and are coded by genes that can be cloned). In practice, we have observed that the "autonomous" laboratory sessions generate many more problems than simply hindering the acquisition of an integrated view of reality. An important aspect concerns objectives. As mentioned, the instructor's objective is that the students should obtain good experimental data. However, "good experimental data" are often thought as a precise "match" of a given observed set of results with the expected set. For example: "was the Lowry calibration curve good?"; "did we get values for the protein samples according to the dilutions made'?"; "could we observe the expected bands in the agarose gel after the miniprcp?" - - and so on, become the most important questions, as if the only objective were to assess the manipulative skills of students. The students tend to be shifted from one method to another with the additional requirement of finishing within the time limits of each lab session, thus leaving them with few opportunities to get sufficient practical expertise to understand what are they doing and why. Lack of this expertise is frequently raised as the explanation for the lack of match between the results obtained by the students and the expected ones. Both the lack of understanding, and the permanent feeling that they do not know how to work properly, disappoints the students - - thus leading to an inappropriate objective on their part, namely just to finish the lab session and go home.

3. The new m e t h o d o l o g y

We changed our schedule in order to make room for extended experimental sessions where students could get involved in technological processes that more closely resemble the true situation of most professional work in pharmaceutical industry, biotechnology, biochemical research and related areas. In the first of the two semesters, the students have lectures and seminars that use problem-based learning methodology [1] that relates to the four main subjects mentioned above. At the end of this first semester, the students get an evaluation during which they have to try to solve real problems (mostly borrowed from recent research articles) that integrate the subjects and where the handling of concepts is much more important than their memorization (to strengthen this bias, students are allowed to use books during the test). Those who pass the test may continue in the second semester with the modified practical laboratory work. In Fig. 1 we outline the steps commonly followed in a technological process. This starts with the identification of the problem, which also has to bc put in context, i.e. viewed as part of a more general situation where we need a better understanding and/or a new practical output. Next, a project must be elaborated by which it is expected to obtain solution(s) to the problem by means of the proper application of techniques in relation to the availability of human and material resources. Once the

ldentificate and put the problem

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processand its results

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Fig. I. Schemeof a technological process describing its principal steps. Arrowheads are used as in flow charts: -,, stimulation; --I, inhibition.

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project is delineated, its execution by means of available technological means is evaluated. This process may dictate a re-elaboration of the project, an adjustment of its goals, or even its interruption, if it is revealed to be an impossible task. If the project continues, its operation and the results produced must be evaluated; this evaluation can modify the way in which the project is executed (or recommend its interruption) and also perhaps modify our understanding of the problem (or reveal that it was misunderstood, and that such a problem did not exist in the way that had been thought). Given that the most important priorities of the "traditional" lab session were to teach experimental techniques, we asked ourselves which techniques were involved. We decided that two classes of techniques were used. One of these, which we will call the general class, required neither intensive use of equipment nor expensive reagents, and therefore could be carried out by all the students in almost all the experimental sessions. These included chemical and enzymatic reactions that measure reaction products by colorimetric methods in three out of the four experimental sessions, and fractionation of different materials by centrifugation in all the four labs. The second, which we will call the specialized class of techniques, included those that made intensive use of relatively expensive equipment and therefore the number of students involved was limited by the availability of equipment. Examples were electrophoresis of DNA and proteins, and chromatography by gel filtration and ion exchange. In these cases only three or four students could work actively, while the others were just required to observe. To design objectives for the students without simultaneously losing the goals of the traditional laboratory schedule, we used/~-galactosidase as a model system able to cover the main subjects treated in our course. This enzyme can be purified by classical methods [2], its biological activity can be measured by a one-step colorimetric reaction by both in vitro [3] and in vivo [4] methods, values for its kinetic parameters and activation energy are available in the literature [5], it participates in carbon metabolism and provides glucose for anabolism or catabolism depending on the cell energy charge [6], the gene cncoding this enzyme in Escherichia coli has been cloned and fully characterized [7-9], its expression and transcriptional regulation includes catabolite repression [ 10,11 ], and there are plenty of wild-type and mutant strains available, as well as plasmids that carry the lacZ structural gene under the control of diverse promoters [12]. In the new schedule we divide the students into three groups (5-10 per group). Each group engages in one activity that they will carry out under supervision of one instructor. The definition of the objectives for each activity is accomplished in two previous seminars among the students and the instructor, and the students arc asked to agree their objectives during the semester. The

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required output is a scientifically explainable result, i.e. a general and reproducible one. As they progress with their respective projects, they must communicate their results both orally to the instructors and to the other students at lab seminars held periodically, and finally, by a written report. The activities suggested by each group in 1997 are given in Fig. 2. Here we observe that all three activities inw)lvc the use of the general class of techniques whereas when the specialized class of techniques was used by three or four students of one group, the others (including other groups) were called upon to observe and provide an explanation, as was done before in the "traditional" laboratory work schedule. Since the model system is common, no significant losses of understanding of techniques are perceived. In the development of the technological process, the students prepare their work plans during the first seminar and, guided by an instructor, they consider the possibilities and think about the equipment they need for the project. In the second seminar, the plans and protocols written by the students are discussed and alterations made when necessary. During the next three lab sessions, the students carry out the work plans already agreed. After these three lab sessions they describe the preliminary results they have obtained as an oral presentation. In this forum the results are evaluated and future activities toward achieving the research objective are discussed with the participation of the other students and the instructors. After this seminar, all groups have another three classes of experimental work and another scminar in the same format. By the last two lab sessions it is expected that the main objectives will already have been met, and so the time may be devoted to collaborative work in which different groups exchange materials and expertise in order to generate new information of mutual interest (this activity is again favoured by the work done with a common model system). Finally, they produce a written report and make the final oral presentation, both of which form the core of the second evaluation of students performance. Using the scheme described here we have observed that the students became much more interested in the projects, since (1) having the whole semester to complete the work they have sufficient time to become familiar with the lab techniques and so gradually shift their attention to what they were doing and why instead of how it should be done, and (2) their success or failure rests in their own hands instead of those of the instructors from the beginning of the second semester, and so lack of results can no longer be explained simply by claiming "lack of expertise". Having both an increased responsibility for the attainment of the experimental objectives proposed by themselves, and the feeling of challenge that accompanied this partial transfer of laboratory work management, students develop a better motivation to working in the lab. By comparison with the "traditional"

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