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JOURNAL OF MICROBIOLOGY & BIOLOGY EDUCATION, May 2015, p. 79-81 DOI: http://dx.doi.org/10.1128/jmbe.v16i1.840

Using Lecture Demonstrations to Visualize Biological Concepts Kristin Polizzotto and Farshad Tamari* Department of Biological Sciences, Kingsborough Community College, Brooklyn, New York, 11235 INTRODUCTION The use of visual aids in biology has traditionally focused on laboratory activities and demonstrations (3, 6, 8, 12, 15–18). However, a limited number of authors have suggested activities suitable for lectures. Such activities reinforce the concepts taught and require less equipment, time, and expense than laboratory activities (1, 4, 9, 13, 14, 19, 20, 22). Moreover, simple demonstrations are easy for students to remember and can be repeated when studying independently. Simple demonstrations that use three-dimensional, concrete objects and kinesthetic processes help students comprehend abstract concepts such as the structure of organic macromolecules, protein synthesis, DNA replication, and gene linkage/recombination. We describe two demonstrations targeted for introductory biology, cell biology, genetics, and molecular biology courses. The demonstrations are lecture oriented, can be used in large classrooms, are inexpensive, and can be easily performed because they use readily available objects as props. We conducted an IRB-approved study showing that student performance is enhanced using these and three additional demonstrations, the description of which can be found at: https://sites.google. com/site/tamarif26. We report the results in the research section of this issue.

PROCEDURE Following are the instructions for two demonstrations that have been successfully used in an introductory biology and genetics course. 1. Macromolecule Monomers and Polymers Students experience challenges in distinguishing the different types of macromolecules, the monomers that comprise each, and the types of bonds and linkages that form the macromolecules. *Corresponding author. Mailing address: Department of Biological Sciences, Kingsborough Community College, 2001 Oriental Boulevard, Brooklyn, New York 11235. Phone: 718-368-5726. Fax: 718-368-4873. E-mail: [email protected].

Begin this demonstration by describing the similarities between the macromolecule classes, including the formation of polymers from monomers by dehydration synthesis reactions in all four classes. Have the students participate in generating a table summarizing the monomers, bonds and linkages, and examples for each macromolecule (Table 1). For the visual part of this demonstration, use a chain or necklace with links. Demonstrate that individual links within the chain represent monomers (monosaccharides, amino acids, or nucleotides). The entire chain represents a carbohydrate, polypeptide, or nucleic acid. Illustrate that connections between the links represent linkages and bonds, and that they are glycosidic linkages, peptide bonds, and phosphodiester bonds for the above macromolecule classes (Fig. 1). 2. Translation Begin by describing the assembly of ribosomes and the molecules involved such as mRNA and tRNA. Illustrate the structure of the ribosome using the drawing shown in Figure 2. First, draw the exit (E), peptidyl (P), and aminoacyl (A) sites of the ribosome (Fig. 2a, EPA). For this demonstration, two student volunteers representing tRNA initially stand in the P and A sites each holding a paper clip representing attached amino acids (Fig. 2a). Take the clip from the student in the P site, illustrating breaking of the bond between the first amino acid (methionine) and the first tRNA, and attach it to the clip (second amino acid) that the student in the A site (second tRNA) is holding (Fig. 2b). Illustrate the formation of a peptide bond by linking the clips. Explain the role of peptidyltransferase catalyzing the formation of a peptide bond. The student in the P site slides to her/his right (E site) and eventually leaves the ribosome while the second student now holding two attached clips (amino acids) moves to the P site. Holding another paper clip (third amino acid), move to the A site (Fig. 2c). Break the bond between the student (tRNA) and the two amino acids he/she is holding and form a peptide bond between the second amino acid and the third amino acid in the A site. The second student slides right, to the E site. Holding three amino acids, slide to the P site and explain how the reaction continues (Fig. 2d).

©2015 Author(s). Published by the American Society for Microbiology. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial-NoDerivatives 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/ and https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode), which grants the public the nonexclusive right to copy, distribute, or display the published work.

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POLIZZOTTO and TAMARI: BIOLOGY CONCEPT VISUALIZATION TABLE 1. Classes of macromolecules, listing monomers, types of linkages (bonds), and examples of monomers and polymers for each macromolecules class. Macromolecule

Monomer

One Example of a Common Monomer

Type of Bond/Linkage

Example of a Common Polymer

Monosaccharide

Glucose

Glycosidic linkages

Starch

Protein

Amino acids

Serine

Peptide bonds

Vimentin

Nucleic acid

Nucleotides

Adenine

Phosphodiester

DNA, RNA

Fatty acids/Glycerol

Palmitic acid

Ester linkages

Triacylglycerol

A

B

Carbohydrate

Lipid

C

D

FIGURE 1.  Monomers (links in chain) linking to form polymers form macromolecules. Each link represents a monomer (monosaccharide, amino acid, and nucleotide), the joining of the links represents glycosidic linkages, peptide bonds, and phosphodiester bonds for polysaccharides, proteins, and nucleic acids, respectively.

CONCLUSION Active student engagement is likely to facilitate learning. Comprehension increases with the number of different learning methods employed, especially those involving kinesthetic learning (2, 5, 7, 10). The use of such low-cost demonstrations has been explored (11, 21) and found to be very successful. These demonstrations provide a visual advantage for students who may be under-prepared before arriving to a college setting, those who may be returning to college after a long break from formal learning, or those who are speaking English as a second language. In each of these cases, a visual demonstration of an abstract concept, particularly one that involves not only an image projected on the screen, but also some type of three-dimensional object and/or kinesthetic experience, will greatly improve their ability to understand and retain the information presented. Another advantage for the use of demonstrations is the ease with which these students can replicate any of these demonstrations later, when studying on their own. The tools are readily available, easy to recall, and simple to put into practice. 80

FIGURE 2.  Demonstration for translation using students with pens. Students represent tRNA while pens represent amino acids (a.a.). a) ribosome structure with exit (E), peptidyl (P), and aminoacyl (A) sites, and placement of first tRNA with first a.a. at P site; b–d) placement of tRNA molecules, breaking of bonds between amino acids and tRNA, and formation of bonds between amino acids, in subsequent steps (see text).

To evaluate the effectiveness of these demonstrations (and three additional ones described at: https://sites.google. com/site/tamarif26) on student learning, we conducted an IRB-approved study at Kingsborough Community College with students in majors general biology, nonmajors human genetics, and majors genetics. The data support our hypothesis (please see the research section of this issue). We have shown that overall, across all courses and all demonstrations, students perform better on tests when the topics are accompanied by demonstrations.

ACKNOWLEDGMENTS The authors would like to thank Drs. Brancaccio-Taras, Hinkley, and Ortiz for reviewing the manuscript and providing

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constructive suggestions. The authors declare that there are no conflicts of interest.

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11. Jakobi, S. 2010. An inexpensive and sage experiment to demonstrate Koch’s postulates using citrus fruit. J. Biol. Educ. 44:190–192. 12. Nurachman, Z., J. Hermawan, Y. Rachmayanti, and L. Baradja. 2003. A simple way to visualize fibrinolysis in the classroom. Biochem. Molec. Biol. Educ. 31:16–19. 13. Ortiz, M. T., L. Taras, and A. M. Stavroulakis. 2000. The Hardy-Weinberg equilibrium—some helpful suggestions. Am. Biol. Teach. 62:20–22. 14. Polizzotto, K., and M. T. Ortiz. 2008. Design projects in human anatomy and physiology. Am. Biol. Teach. 70:230–234. 15. Porta, A. R., and P. Dhawan. 2006. How scientists use critical-thinking skills. J. Coll. Sci. Teach. 35:14–17. 16. Runge, S. W., B. J. F. Hill, and W. M. Moran. 2006. A simple classroom teaching technique to help students understand Michaelis-Menten kinetics. CBE Life Sci. Educ. 5:348–352. 17. Sharma, P., D. R. D’Souza, D. Bhandari, V. Parashar, V., and N. Capalash. 2003. Demonstration of the principle of restriction endonuclease cleavage reactions using thermostable BfII from Anoxybacillus flavithermus. Biochem. Molec. Biol. Educ. 31:392–396. 18. Shmaefsky, B. R. 2005. A fruity biochemistry demonstration. J. Coll. Sci. Teach. 34:64–65. 19. Stavroulakis, A. M. 2005. Meio-Socks and other genetic yarns. Am. Biol. Teach. 67:233–238. 20. Straits, W. J., and R. R. Wilke. 2006. Interactive demonstrations: examples from biology lectures. J. Coll. Sci. Teach. 35:58–59. 21. Weise, L. 2006. Simple inexpensive respirometers. Am. Biol. Teach. 68:293–295. 22. Wellnit z , T. 20 06. Using group per formances to demonstrate concepts in large biology classes. Am. Biol. Teach. 68:238–240.

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Using lecture demonstrations to visualize biological concepts.

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