Communication pubs.acs.org/jchemeduc
A Stimulating Chemistry Program for Compulsory School Students: Four Hands-On Experiments Investigating Proteins Martin Lundqvist* Department of Biochemistry and Structural Biology, Centre for Molecular Protein Science, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden Åbyskolan, Upper Secondary School, Storg. 9, 26480 Klippan, Sweden S Supporting Information *
ABSTRACT: The western world has had a general decline in student interest for natural sciences. A 2−4 h program is described that can generate interest in chemistry by letting compulsory students conduct experiments that are connected to their life.
KEYWORDS: Elementary/Middle School Science, High School/Introductory Chemistry, Biochemistry, Laboratory Instruction, Public Understanding/Outreach, Hands-On Learning/Manipulatives, Enzymes, Food Science, Proteins/Peptides
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A more elaborated description along with the materials required can be found in the Supporting Information. The program starts with a short, ∼10 min, introduction to proteins (what are proteins, what are they made up from, and some examples of different functions). The introduction is designed for the knowledge level of the students so not to lose their interest by going too deep into the subject.
n outreach program focusing on the biochemistry of everyday items has been developed that is suitable for students who are almost finished with compulsory school1 (in Sweden when they are 14−15 years); however, the experiments can be adapted to students of other age groups. Sweden, similar to most of the western world, has experienced a decline in the interest for education in chemistry at university level.2 In an attempt to change this trend, The Swedish National Committee for Chemistry launched a project called kemilektorslänken3 in 2009 that aims to bring the universities closer to the upper secondary schools by hiring Ph.D.s (in chemistry) to work at both locations and act as a link between the university and the compulsory school (kemilektorslänk = chemistry lecturer link) in line with what Cacciatore called for in the article from 2011.4 All of the municipality students studying the last year at compulsory school visited the research lab at the upper secondary school (established at the school due to the school’s participation in the kemilektorslänk project), in groups of 6−12 students on 14 occasions.
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EXPERIMENT 1 After the introduction it is time for experiment 1, which illustrates that some proteins (proteases) can cleave other proteins; more specifically how actinidin, a protease found in kiwi, breaks the protein network of gelatin. This chemistry is useful if you want to make a gelatin-covered fresh fruit dessert.
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EXPERIMENT 2 Experiment 2 illustrates how a protein can speed up a reaction and how this effect can be inhibited by a competitive inhibitor. This experiment relates to human metabolism and leaves plenty of room for going deep into the metabolism. The experiment is introduced by pointing out that the reaction is a step in the citric acid cycle, one of the constantly ongoing reaction schemes that keep us alive by generating energy. The experiment studies the activity of the enzyme, succinate dehydrogenase (SDH), that catalyzes the transformation of succinate to fumarate. Students have to learn how to use pipetman (this step can be neglected if students are already familiar with them).
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PROGRAM OVERVIEW An intriguing 2−4 h program, depending on the number of the experiments completed, has been put together in an attempt to attract compulsory school students to natural science programs at upper secondary school (a prerequisite for increasing the number of students in chemical education at the university level). The presentations and discussions can easily be adapted to the level of the students, from beginners up to students that study chemistry at the university level. The session is composed of four experiments with a common denominator, proteins. © 2014 American Chemical Society and Division of Chemical Education, Inc.
Published: January 31, 2014 455
dx.doi.org/10.1021/ed3002978 | J. Chem. Educ. 2014, 91, 455−456
Journal of Chemical Education
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EXPERIMENT 3
Communication
EXPERIMENT 4 In experiment 4, the break down of different alcohols (addressing substrate specificity) by the enzyme, alcohol dehydrogenase (ADH), is studied spectrophotometrically. Spectra data are given in the Supporting Information for laboratories without this equipment. A treatment for methanol poisoning is discussed.
Experiment 3 is an example of a biochemical technique and an introduction to the complexity of biological fluids. A discussion about “What is milk?”, “What does milk contain?”, and “If someone is or knows someone that is intolerant to bovine milk?” starts the session. The last question is “How is lactosefree milk produced?”. After the discussion, the students separate the disaccharide, lactose, from proteins and fat in milk using size-exclusion chromatography. Lactose is detected using the Benedict’s reagent. When the students have finished the experimental part of the separation of lactose from protein, it is time for drawing conclusions, adapted to the student level, from the results in experiments 1, 2, and 3 (see the Supporting Information).
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SUMMARY The students obtained results from all of the experiments that visually confirmed the scientific concepts (Figure 1) and they were able to gain an appreciation of the value of science in their everyday lives. After such a program, the students were quite satisfied and happy.5 Figure S1 (in the Supporting Information) shows an evaluation of how the students experienced the lab. More than 75% of the students were, in general, very positive to the experience.
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ASSOCIATED CONTENT
S Supporting Information *
Outcome of the survey the participating students filled in after they had performed the four experiments, detailed information for the setup of the experiments, more data for the results of the different experiments and suggestions for discussions with the students, table with raw data for the ADH experiment. This material is available via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS Marianne and Marcus Wallenberg Foundation and Magn. Bergvall Foundation for financial support are acknowledged. Celia Cabaleiro Lago is thanked for her comments.
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REFERENCES
(1) The educational system in Sweden is as follows: preschool, age 6 years; compulsory school, ages 7−16 years; upper secondary school, ages 16−19 years; and university, 2−5 years. See also Skolverket (the Swedish Education System). http://www.skolverket.se/omskolverket/andra-sprak-och-lattlast/in-english/the-swedish-educationsystem (accessed Jan 2014). (2) OECD Evolution of Student Interest in Science and Technology Studies: Policy Report; OECD Global Science Forum: Paris, 2006. (3) Kemilektorslanken. www.kemilektorslanken.se (accessed Jan 2014). (4) Cacciatore, K. L. An Urgent Call for Academic Chemists To Engage in Precollege Science Education. J. Chem. Educ. 2011, 88, 248. (5) If you work with students with limited knowledge (or students that are not interested in natural science), my experience for a successful (and inspiring) session is to have small groups, not more than 8 students.
Figure 1. Showing results from experiments 1−4. In (1), the water released from the gel due to the actinidin breakage of the collagen network is clearly visible around the kiwi slice, whereas no water is found in the gel surrounding the apple slice. In (2) the four samples from experiment are shown. In tube a, the anaerobic reaction already decolored the solution, tube b is still blue due to the inhibition of SDH, tube c (which has 5 times higher substrate concentration) is at this time point in between the processes in tube 1 and 2, and in tube d, nothing has happened as the yeast is dead. In (3) the results from the separation of the milk protein (purple color, mainly in fraction c) and lactose (orange color, mainly fractions e−h) are shown. In (4) ADHs enzymatic activity is shown with different alcohol as substrates: black diamonds = autocatalysis, red squares = ethanol, orange triangles = methanol. 456
dx.doi.org/10.1021/ed3002978 | J. Chem. Educ. 2014, 91, 455−456
