Portage Microbiology Exam #6 Rated A+

True or False: Because the genome is contained within an enclosed space, (much like the nucleus of a cell) viruses are classified as eukaryotic Ans- False. Viruses are neither eukaryotic nor prokaryotic Describe the ...

True or False: Because the genome is contained within an enclosed space, (much like the nucleus of a cell) viruses are classified as eukaryotic Ans- False. Viruses are neither eukaryotic nor prokaryotic Describe the two basic components of a virus (short answer) Ans- A virus has 1. genomic material comprised of either DNA or RNA and 2. a capsid, a membrane-like protective structure that contains the genetic material, similar to the nucleus of a eukaryotic cell The _____ surrounds the capsid of some viruses Ans- Envelope The envelope surrounds the _____ of some viruses Ans- Capsid True or False: You would expect to see a viral envelope on a virus infecting a plant cell AnsFalse. The overwhelming majority of animal viruses are enveloped whereas the majority of plant or bacteria-infecting viruses are not True or False: You would expect to see a viral envelope on a virus infecting a bacterial cell AnsFalse: Not all the viruses have envelopes Rank the following viruses based on their size from largest to smallest: orthomyxovirus, poliovirus, variolavirus Ans- Variolavirus>Orthomyxovirus>Poliovirus Rank the following viruses based on their size from largest to smallest:Paramyxovirus, Poliovirus, Smallpox virus Ans- Smallpox>Paramyxovirus>Poliovirus True or False: Viral replication occurs after it attaches and enters the host cell Ans- True. The viral genome is never replicated before attachment and entry True or False: Highly infectious viruses undergo genome replication prior to viral attachment and entry. Ans- False. The viral genome is never replicated before attachment and entry regardless of its level of infectivity. Place the following viral life cycle steps in order beginning with viral attachment and provide a description of each step (short answer) Ans- Uncoating: the viral capsid disassembles Release: New virus particles are produced and leave the cell Replication: the viral genome is the 'blueprint' to make copies of itself Attachment: viral receptors bind to host proteins on the surface of the cell Entry: the virus fuses with the host membrane and enters the cell New Infection: newly produced viruses that left the host cell now go on to infect new cells A virus that infects bacteria is called a _____ and contains a _____ -side polygon capsid (fill in the blank) Ans- Bacteriophage; 20-sided True or False: Structurally bacteriophages are similar to viruses that infect animals Ans- False. Bacteriophages have a distinct composition and structure True or False. Structurally, bacteriophages are distinct from viruses that infect plant or animal cells. Ans- True. Bacteriophages are structurally distinct from viruses that infect plant and animals cells. Identify the following components of a bacteriophage (picture) Ans- 1. Capsid 2. Collar 3. Tail 4. Base 5. Tail fibers Describe the main differences between lytic and temperate phages (short answer) Ans- Lytic bacteriophages replicate within the host bacteria until it ruptures, whereas temperate phages primarily exist in a non-replicative state that does not kill the host cell Lytic phages replicate all viral proteins needed for the assembly of new virus particles whereas lysogenic phage genomes are integrated into the host genome but production of viral proteins is suppressed Based on the following image, would you expect the viral titer to be high or low? Why? (cloudy) Ans- Low. As turbidity is a function of the number of intact bacterial cells present in the media, the amount of virus contained within the above tube must be low. As the lytic continues more and more bacterial cells will be destroyed, effectively clearing the media. Which of the following cannot be spread via airborne particles A. Measles B. Mumps C. Rubell