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Bacteriology at UW-Madison |
183. Define the term host as it relates to viruses. Viruses can be defined in either biological or chemical terms. Give both kinds of definitions.
184. From what you know about cell function and virus function, would you say viruses are living or dead? Why?
185. What is the basis of the system for the classification of the viruses?
186. Outline the steps involved in the replication of a lytic bacteriophage starting with a free virus particle and a cell and ending with a lysed cell and 100 new virus particles. Describe the molecular and biochemical events which occur during the viral replication cycle.
187. Describe the events which occur on an agar plate containing a bacterial "lawn", which result when a single bacteriophage particle causes the formation of a bacteriophage plaque.
188. List several examples of "early proteins" synthesized in E. coli cells infected with a lytic phage. What are the "late proteins" coded for by phage DNA?
189. Illustrate with diagrams and written designations a model for the life cycle of a temperate (lysogenic) virus such as E. coli phage lambda (l). What is the role of the lambda repressor protein in the lambda infection process?
190. What are the similarities between a Iysogenic bacterial cell and an animal tumor cell which has been transformed by an oncogenic (tumor-producing) virus?
191. Explain the relationship between lysogeny and virulence in Corynebacterium diphtheriae.
192. The life cycle (mechanisms of nucleic acid replication) of certain single-stranded RNA viruses, single-stranded DNA viruses and double-stranded RNA viruses are known and understood by virologists and molecular biologists. Without their detailed knowledge, but with your general understanding of DNA and RNA replication, construct a scheme which might illustrate the life cycles of these unusual viruses.
193. Can you think of any reason why most bacterial viruses have tails and no animal or plant viruses possess them?
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Edited 0n Jan 4, 2002 by Kenneth Todar University of Wisconsin-Madison Department of Bacteriology.