Module 2: The Cell

Life takes many forms, from giant redwood trees towering hundreds of feet in the air to the tiniest known microbes, which measure only a few billionths of a meter. Humans have long pondered life’s origins and debated the defining characteristics of life, but our understanding of these concepts has changed radically since the invention of the microscope. In the 17th century, observations of microscopic life led to the development of the cell theory: the idea that the fundamental unit of life is the cell, that all organisms contain at least one cell, and that cells only come from other cells.

Despite sharing certain characteristics, cells may vary significantly. The two main types of cells are prokaryotic cells (lacking a nucleus) and eukaryotic cells (containing a well-organized, membrane-bound nucleus). Each type of cell exhibits remarkable variety in structure, function, and metabolic activity (Figure 3.1). This chapter will focus on the historical discoveries that have shaped our current understanding of microbes, including their origins and their role in human disease. We will then explore the distinguishing structures found in prokaryotic and eukaryotic cells.

Image: Microorganisms vary visually in their size and shape, as can be observed microscopically; but they also vary in invisible ways, such as in their metabolic capabilities. Source: a, e, f: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by NIAID; credit c: modification of work by CSIRO; credit d: modification of work by “Microscopic World”/YouTube

 Upon completion of this module, you will be able to:

1. Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms (Course Outcomes # C.O. 1 and 5)
2. Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation (C.O. 1 and 5)
   
3. Explain the key points of cell theory and the individual contributions of Hooke, Schleiden, Schwann, Remak, and Virchow. (C.O. 1 and 5)
4. Explain the key points of endosymbiotic theory and cite the evidence that supports this concept. (C.O. 1)  
5. Explain the contributions of Semmelweis, Snow, Pasteur, Lister, and Koch to the development of germ theory. (C.O. 1, 3, 4, and 5)   
6. Explain the distinguishing characteristics of prokaryotic cells (C.O. 1)  
7. Describe common cell morphologies and cellular arrangements typical of prokaryotic cells, and explain how cells maintain their morphology. (C.O. 1)
8. Describe internal and external structures of prokaryotic cells in terms of their physical structure, chemical structure, and function. (C.O. 1)
9. Compare the distinguishing characteristics of bacterial and archaeal cells. (C.O. 1)
10. Explain the distinguishing characteristics of eukaryotic cells. (C.O. 1)
11. Describe internal and external structures of eukaryotic cells in terms of their physical structure, chemical structure, and function. (C.O. 1)
12. Describe structures and organelles unique to eukaryotic cells. (C.O. 1)
13. Compare and contrast similar structures found in prokaryotic and eukaryotic cells. (C.O. 1 and 5)
14. Describe the processes of eukaryotic mitosis and meiosis, and compare to prokaryotic binary fission (C.O. 1)
15. Using a digital tool, develop a concept map centered around the Prokaryotic Cell. (C.O. 1 and 6)
    

To achieve these objectives: 

Welcome to this module! To be successful, please complete the activities in the sequence listed below. Each activity is designed to build your microbiology knowledge while also strengthening essential digital, scientific, and communication skills needed for today’s workforce.

1. Read the Module 2 Introduction:  This provides the purpose of the module, key themes, and the learning outcomes you are expected to achieve by the end.
2. Read Chapter 2 in Medical Microbiology for Nursing and Allied Health: A Louisiana Perspective
3. Complete the [following activities in order. Check off each box as you go.]

You will find the following resources and activities in this module at the Pressbooks website. Click on the links below to access or complete each item.