PORTAGE LEARNING BIOD 171
MODULE 6 EXAM QUESTIONS WITH
DETAILED ANSWERS
, True or False: viruses can be classified as prokaryotic or eukaryotic - ANSWERFalse.
Viruses are neither prokaryotic or eukaryotic
What is an obligate intracellular parasite? - ANSWERviruses 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? - ANSWERa membrane-like protective structure that contains
genetic material similar to 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? - ANSWERThe 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? -
ANSWERDue 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? - ANSWERThe 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? - ANSWERFor all
viruses, the genome is replicated following attachment and entry, never before.
Describe the basic steps of the viral life cycle. - ANSWER1. 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? - ANSWERA virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either
animals or plants? - ANSWERBacteriophages possess an icosahedral capsid head
group and a helical tail. Attached to the tail are fibrous extensions or 'legs' that aid in
MODULE 6 EXAM QUESTIONS WITH
DETAILED ANSWERS
, True or False: viruses can be classified as prokaryotic or eukaryotic - ANSWERFalse.
Viruses are neither prokaryotic or eukaryotic
What is an obligate intracellular parasite? - ANSWERviruses 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? - ANSWERa membrane-like protective structure that contains
genetic material similar to 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? - ANSWERThe 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? -
ANSWERDue 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? - ANSWERThe 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? - ANSWERFor all
viruses, the genome is replicated following attachment and entry, never before.
Describe the basic steps of the viral life cycle. - ANSWER1. 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? - ANSWERA virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either
animals or plants? - ANSWERBacteriophages possess an icosahedral capsid head
group and a helical tail. Attached to the tail are fibrous extensions or 'legs' that aid in
