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Kingsborough Community College
May 2015
Using Lecture Demonstrations to Visualize
Biological Concepts
Kristin Polizzotto
CUNY Kingsborough Community College
Farshad Tamari
CUNY Kingsborough Community College
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Polizzotto, K. & Tamari, F. (2015). Using Lecture Demonstrations to Visualize Biological Concepts. Journal of Microbiology &
Biology Education, 16(1), 79-81. doi:10.1128/jmbe.v16i1.840.
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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.
Volume 16, Number 1
Journal of Microbiology & Biology Education
79
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
Journal of Microbiology & Biology Education
Volume 16, Number 1
POLIZZOTTO and TAMARI: BIOLOGY CONCEPT VISUALIZATION
constructive suggestions. The authors declare that there are
no conflicts of interest.
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