Download Chapter 14: The Viruses and Virus

Chapter 14
The Viruses and Virus-like Agents
Chapter Summary and Essay Questions
The nature and significance of viruses are explored in Chapter 14. A short history of virology is
followed by discussions of the structure and replication cycles of viruses. Surveys of viral
detection, inhibition, and inactivation are included. Viruslike agents, especially prions, are
included in the chapter material. After you have studied the chapter, you should be able to answer
the following essay questions:
a. Assess the role of electron microscopy and the development of the test tube cultivation of
viruses to the crucial growth of virology.
b. Compare the size of viruses with the size of bacteria and other microorganisms.
c. Identify the three major shapes that viruses can take, and explain the components that
make
up a virus.
d. Distinguish between the host range and tissue tropism exhibited by viruses.
e. Explain how virus families are split into two nucleic acid groups and discuss how each
group is further divided.
f. Describe each of the five steps that take place during bacteriophage replication.
g. Compare the replication of animal viruses with that of bacteriophages, and note the
exceptions in the processes for DNA and RNA viruses.
h. Explain the difference between a prophage and provirus.
i. Describe the characteristic cytopathic effects produced by some viruses.
j. List the different methods for detecting viruses, and give examples of each method where
possible.
k. Discuss the role of viruses as cancer-causing agents.
l. Assess the roles of genetic recombination and mutation in creating new viruses.
m. Discuss how the environment and social conditions can result in new viruses appearing.
n. Compare the three hypotheses for the origin of viruses.
o.
Describe the chemical nature of prions and how they are thought to cause transmissible
spongiform encephalopathies.