Description:  A small group activity which uses a problem-based approach to introduce students to the differential action of antibiotics on the components of bacterial and archaeal cell walls.

Audience: Allied health majors, Microbiology/biology majors

Microbiology Keywords:   Antibiotic resistance, Antibiotics, Case Studies, Cell wall

Pedagogy Keywords:   Problem-based learning

Science Discipline Keywords:  Bacteriology, Microbiology

Core Themes:    Theme 1: Microbial cell biology, Theme 6. Teaching and learning

Core Skills:   Thinking: Analysis

Learning Time: 1 hour in class with homework assigned prior to the class

Learning Objectives

At the completion of this activity students will be able to:

Background

Students are given a review sheet before the class in which the small group activity occurs. This sheet covers the basic cell wall structures for gram-positive and gram-negative bacteria and archaea. From this review or from their class materials, students should be able to identify, describe, and label the appropriate structures on a model cell wall using the following terms:

PROCEDURE

Materials.

One worksheet for every student

Student Version.

Instructor Version.

Instructor Version

Safety Issues.

None

Suggestions for Determining Student Learning.

The primary mechanism for determining student learning is the answers they provide to the questions on the worksheet. We have also used as a secondary assessment tool a pre- and posttest given to students the first and last day of lab recitation (see field testing section for details).

Field Testing.

During the spring of 2007, we developed a pre- and posttest that was given to students at the first lab recitation session before any small group or lab activity covered the material being tested. This same test was also given to students on the last day of lab recitation. With this design, our data provides insight into student learning and the level of material retention. Using questions 1, 4, and 5 from the test, we quantified student learning on the function of the cell wall and antibiotics. Test scores for question 1 improved from 68% (n = 75) to 90% (n = 71), scores on question 4 improved from 68% (n = 75) to 90% (n = 71) where scores for question 5 improved from 61% (n = 75) to 92% (n = 71).

Student Data.

None available at time of submission.

SUPPLEMENTARY MATERIALS

Possible Modifications.

This exercise could be modified in at least two different ways. If using it with majors in an upper-level course, the “helpful background information” can be removed and the description of each unknown antibiotic could be changed to the specific site of action of each antibiotic. In this way, the activity could cover the modes of action of the antibiotics at a greater molecular level. If working with allied health students, the focus of the activity could be changed to reflect the differences between eukaryotic and prokaryotic cells and how antibiotics specifically target one and not the other.

References.

1.  Foster, J. W., and J. L. Slonczewski.  2008.  Cell structure and function, p. 82–97.  In Microbiology an evolving science, 1st ed.  W. W. Norton and Co., New York, NY.  

2.  Madigan, M. T., and J. M. Martinko.  2005.  Cell structure and function, p. 66–81.  In Brock biology of microorganisms, 11th ed.  Pearson Prentice Hall, Upper Saddle River, NJ. 

3.  Paustian, T.  2001.  More cell wall.  http://lecturer.ukdw.ac.id/dhira/BacterialStructure/MoreCellWall.html.

4.  Paustian, T.  2002.  Cell wall. http://lecturer.ukdw.ac.id/dhira/BacterialStructure/CellWall.html. 

5.  Schaechter, M., J. L. Ingraham, and F. C. Neidhardt.  2006.  Prokaryotic cell structure and function:  envelopes and appendages, p. 22–31.  In Microbe. ASM Press, Washington, DC.  

Answer Keys.