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Portage Learning BIOD 171 Module 6 Questions and Answers (100% Pass)
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Portage Learning BIOD 171 Module 6 Questions and Answers (100% Pass)
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©PREP4EXAMS@2024 [REAL-EXAM-DUMPS] Monday, July 29, 2024 12:15 PMPortage Learning BIOD 171 Module 6
Questions and Answers (100% Pass)
True or False: viruses can be classified as prokaryotic or eukaryotic - ✔️✔️False. Viruses
are neither prokaryotic or eukaryotic
What is an obligate intracellular parasite? - ✔️✔️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? - ✔️✔️a 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? - ✔️✔️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? - ✔️✔️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? - ✔️✔️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.
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, ©PREP4EXAMS@2024 [REAL-EXAM-DUMPS] Monday, July 29, 2024 12:15 PM
What must happen before viral replication of its genome can occur? - ✔️✔️For all viruses,
the genome is replicated following attachment and entry, never before.
Describe the basic steps of the viral life cycle. - ✔️✔️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? - ✔️✔️A virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either
animals or plants? - ✔️✔️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? - ✔️✔️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.
Describe the appearance of a bacterial culture infected with virus at the time of infection
versus later once viral replication is occurring at a high rate. - ✔️✔️During the initial
inoculation of virus and bacteria, the media has a high degree of turbidity (cloudiness).
However, as the lytic cycle progresses and more and more bacterial cells are destroyed,
the culture media turns from turbid to clear, as turbidity is a function of the number of
intact bacterial cells present in the media. Thus, as bacterial cell numbers decrease due
to lysis, the media becomes clearer.
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