True or False: viruses can be classified as prokaryotic or eukaryotic - vV False. Viruses are neither
prokaryotic or eukaryotic
What is an obligate intracellular parasite? - v V/viruses cannot replicate unless inside a living host
cell. As a parasite, a virus depends on its living host to provide the framework (proteins, etc) to
replicate—to make additional copies of itself.
What is a viral capsid? - v'v'a membrane-like protective structure that contains genetic material
similarto nucleus of eukaryotic cells.
What is the viral envelope, and what does the presence (or absence) of it tell you about the type of
virus? - vV The envelope surrounds the viral capsid, is derived from the host cell membrane and
serves as an additional barrier to the external environment. The overwhelming majority of animal
viruses are enveloped whereas the majority of plant or bacteria-infecting viruses are not.
What type of microscope would be used to study the shape of a viral capsid? - v/ Due to its size
(~30-150 nm) most viral capsids must be visualized via electron microscopy.
How does the viral envelope both aid in cell entry as well as hide it from being detected by the
immune system? - v V' The viral envelope contains the necessary proteins required for interaction
with host cells. As the envelope is derived from the host cell membrane, this
, camouflages the virus and lowers the likelihood of immune detection by making it appear similar to
the normal biological host cell.
What must happen before viral replication of its genome can occur? - v'V/For all viruses, the genome
is replicated following attachment and entry, never before.
Describe the basic steps of the viral life cycle. - vV 1. Attachment: Viral receptors bind to host
proteins on the surface of the cell.2. Entry: The virus fuses with the host membrane and enters the
cell3. Uncoating: (where applicable) the viral capsid disassembles4. Replication: The viral genome
provides the 'blueprint' to make copies of itself5. Exit: New viruses are produced and leave the cell6.
New infection: Newly produced viruses leave the host cell and go on to infect new cells. The process
outlined above now restarts.
What is a bacteriophage? - v VA virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either animals or
plants? - vV Bacteriophages possess an icosahedral capsid head group and a helical tail.
Attached to the tail are fibrous extensions or 'legs' that aid in binding host cells. Notably, this
particular structural arrangement has not been observed among viruses that infect either animals or
plants.
Which viral replicative process results in the destruction of the host cell? - v/ The lytic replication
cycle occurs when a bacteriophage replicates within a host until it ruptures, effectively destroying
the host bacterial cell. The phrase lytic stems from 'lysis', meaning to rupture or disintegrate
(breakdown) a cell.
prokaryotic or eukaryotic
What is an obligate intracellular parasite? - v V/viruses cannot replicate unless inside a living host
cell. As a parasite, a virus depends on its living host to provide the framework (proteins, etc) to
replicate—to make additional copies of itself.
What is a viral capsid? - v'v'a membrane-like protective structure that contains genetic material
similarto nucleus of eukaryotic cells.
What is the viral envelope, and what does the presence (or absence) of it tell you about the type of
virus? - vV The envelope surrounds the viral capsid, is derived from the host cell membrane and
serves as an additional barrier to the external environment. The overwhelming majority of animal
viruses are enveloped whereas the majority of plant or bacteria-infecting viruses are not.
What type of microscope would be used to study the shape of a viral capsid? - v/ Due to its size
(~30-150 nm) most viral capsids must be visualized via electron microscopy.
How does the viral envelope both aid in cell entry as well as hide it from being detected by the
immune system? - v V' The viral envelope contains the necessary proteins required for interaction
with host cells. As the envelope is derived from the host cell membrane, this
, camouflages the virus and lowers the likelihood of immune detection by making it appear similar to
the normal biological host cell.
What must happen before viral replication of its genome can occur? - v'V/For all viruses, the genome
is replicated following attachment and entry, never before.
Describe the basic steps of the viral life cycle. - vV 1. Attachment: Viral receptors bind to host
proteins on the surface of the cell.2. Entry: The virus fuses with the host membrane and enters the
cell3. Uncoating: (where applicable) the viral capsid disassembles4. Replication: The viral genome
provides the 'blueprint' to make copies of itself5. Exit: New viruses are produced and leave the cell6.
New infection: Newly produced viruses leave the host cell and go on to infect new cells. The process
outlined above now restarts.
What is a bacteriophage? - v VA virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either animals or
plants? - vV Bacteriophages possess an icosahedral capsid head group and a helical tail.
Attached to the tail are fibrous extensions or 'legs' that aid in binding host cells. Notably, this
particular structural arrangement has not been observed among viruses that infect either animals or
plants.
Which viral replicative process results in the destruction of the host cell? - v/ The lytic replication
cycle occurs when a bacteriophage replicates within a host until it ruptures, effectively destroying
the host bacterial cell. The phrase lytic stems from 'lysis', meaning to rupture or disintegrate
(breakdown) a cell.
