Portage Microbiology Exam #6
1). 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
2). 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
3). The _____ surrounds the capsid of some viruses
Ans: Envelope
4). The envelope surrounds the _____ of some viruses
Ans: Capsid
5). True or false: you would expect to see a viral envelope on a virus infecting a plant cell
Ans: False. The overwhelming majority of animal viruses are enveloped whereas the
majority of plant or bacteria-infecting viruses are not
6). True or false: you would expect to see a viral envelope on a virus infecting a bacterial cell
Ans: False: Not all the viruses have envelopes
7). Rank the following viruses based on their size from largest to smallest: orthomyxovirus,
poliovirus, variolavirus
Ans: Variolavirus>Orthomyxovirus>Poliovirus
8). Rank the following viruses based on their size from largest to smallest:paramyxovirus,
poliovirus, smallpox virus
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, Ans: Smallpox>Paramyxovirus>Poliovirus
9). 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
10). 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.
11). 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
12). A virus that infects bacteria is called a _____ and contains a _____ -side polygon capsid (fill in
the blank)
Ans: Bacteriophage; 20-sided
13). True or false: structurally bacteriophages are similar to viruses that infect animals
Ans: False. Bacteriophages have a distinct composition and structure
14). 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.
15). Identify the following components of a bacteriophage (picture)
Ans: 1. Capsid
2. Collar
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1). 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
2). 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
3). The _____ surrounds the capsid of some viruses
Ans: Envelope
4). The envelope surrounds the _____ of some viruses
Ans: Capsid
5). True or false: you would expect to see a viral envelope on a virus infecting a plant cell
Ans: False. The overwhelming majority of animal viruses are enveloped whereas the
majority of plant or bacteria-infecting viruses are not
6). True or false: you would expect to see a viral envelope on a virus infecting a bacterial cell
Ans: False: Not all the viruses have envelopes
7). Rank the following viruses based on their size from largest to smallest: orthomyxovirus,
poliovirus, variolavirus
Ans: Variolavirus>Orthomyxovirus>Poliovirus
8). Rank the following viruses based on their size from largest to smallest:paramyxovirus,
poliovirus, smallpox virus
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, Ans: Smallpox>Paramyxovirus>Poliovirus
9). 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
10). 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.
11). 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
12). A virus that infects bacteria is called a _____ and contains a _____ -side polygon capsid (fill in
the blank)
Ans: Bacteriophage; 20-sided
13). True or false: structurally bacteriophages are similar to viruses that infect animals
Ans: False. Bacteriophages have a distinct composition and structure
14). 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.
15). Identify the following components of a bacteriophage (picture)
Ans: 1. Capsid
2. Collar
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