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Chapter 19
Viruses and Prokaryotes
CHAPTER OUTLINE
Viruses
A virus consists of nucleic acid surrounded by a protein coat
Bacteriophages are viruses that attack bacteria
Viruses reproduce at the expense of their host cells
Some viruses integrate their DNA into the host DNA
Some viruses infect animal cells
Some viruses infect plants
Viroids and prions
Prokaryotes
Prokaryotic cell structure is simpler than eukaryotic cell structure
Some prokaryotes have specialized structures
Prokaryotes have diverse methods of obtaining organic molecules
Focus On: Problems Associated with Bacteria in Wastewater
CHAPTER OBJECTIVES
1. Characterize viruses and explain why they are not grouped in any of the three domains or
six kingdoms.
2. Contrast lytic and lysogenic cycles.
6. Characterize the metabolic diversity of prokaryotes using the following terms: autotroph
LECTURE OUTLINE
I. What do we do with viruses?
A. How are viruses different from cellular organisms?
II. What are viroids and prions?
III. How can we describe prokaryotes?
A. What kingdoms contain the prokaryotes?
B. How are prokaryotes different from eukaryotes?
1. What is different about the cell structure?
C. How do prokaryotes obtain organic molecules for their energy needs?
1. Distinguish between heterotrophs and autotrophs.
2. Distinguish between photosynthetic and chemosynthetic prokaryotes.
D. How do prokaryotes differ in their needs for oxygen?
1. Distinguish between aerobes and anaerobes.
KEY TERMS
aerobic, p. 373
autotroph, p. 372
bacillus, p. 370
endospore, p. 371
facultative anaerobe, p. 373
fecal coliform test, p. 377
obligate anaerobe, p. 373
peptidoglycan, p. 370
pilus, p. 371
TEACHING TIPS
1. Students are interested in organisms that cause disease. This chapter offers an opportunity
to discuss epidemiology, microbes in the environment, and sanitation. Stories such as the
2. Remind students of the many beneficial aspects of bacteria, such as their use in genetic
engineering, their role as environmental decomposers and nutrient recyclers, the
3. Give students petri dishes of bacteria nutrient agar to expose in any way they like. Tell
them how to use a swab or filter paper to inoculate their plate, and caution them to wash
carefully afterwards “just in case.” They can expose the plate to the air in their room, the