1.What are two minimal structural features needed to fit the above definition?


2. All cells contain double-stranded DNA genomes that may be circular or linear.    In contrast, describe the variety of viral genomes that can exist                       using these same terms.


3. c.   Most Bacterial genomes range in length from 1000-5000 kilobase pairs (kbp) of DNA.  Most viral genomes fall into the range defined by the H-1 parvovirus and the human cytomegalovirus.  Look up the genome sizes in base pairs (bp) of these two representative viruses.


4. c.   Describe (or give an example) to illustrate the major differences between the following: a “naked virus”, an enveloped virus, and a complex virus.



5. c.    Although viruses are “metabolically inert” outside a host cell, in some viruses one or more key enzymes are “packaged” within the virion.  Give two examples of virions that contain enzymes; name the enzymes and explain their purpose.


6. The first steps in viral replication are viral attachment & penetration.


7.Explain the difference between viral attachment and penetration. Which of the two steps above represents the true beginning of  infection?


8.“The attachment of a virion to a host cell is highly specific.”   Explain this statement.


9.a.   Explain how cells may be permissive  or not permissive  for the replication cycle of a virus.


10. Briefly describe the steps by which a bacteriophage T4 enters an  E. coli cell.


11. a.   Bacteriophage lambda is an example of a temperate virus.  Birefly describe the differences between the following two pathways which are available to a temperate virus.


12.   Lysogeny versus  lytic pathway.  (What is a  provirus/prophage? )


13.  Describe the structural form of a  viroid.


14. What essential feature of a virus is missing from a viroid?



15. a.   Name a disease caused by a viroid and the host infected.


16.a.   What is most unusual about prion replication?


17.a.   Collectively, animal prion diseases are known as __ and a specific example is __.


18.a.   By convention in virology, messenger RNA (mRNA) is said to be of the (+) configuration and the complement is of the (-) configuration.  Briefly, distinguish between a positive-strand RNA virus and a negative-strand RNA virus in terms of its “readiness” to function directly as mRNA after infecting a cell.


19.Briefly describe the diversity of animal viruses in terms of type of nucleic acid genome, shape, size, and presence/absence of an envelope.  



20.List four possible effects that animal viruses may have on cells they infect


21.a.   Describe the distinctive viruses that infect hyperthermophilic Crenarchaeota in Domain Archaea.


22.a.   Most bacteriophages have a double-stranded DNA genome.  Name an example:


23.a.   What type of genome does Phage MS2 have?


24.a.   Name a bacteriophage that has a circular single-stranded DNA genome.


25.What is the name of the mechanism, different from the semiconservative replication of cellular DNA, that some viruses with ssDNA genomes use?









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