Approved Answers.
What is the viral envelope, and what does the presence (or absence) of
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it tell you about the type of virus?
_;- _;- The viral envelope surrounds the
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viral capsid and serves as an additional barrier to the external
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environment. The majority of animal viruses are enveloped where as _;- _;- _;- _;- _;- _;- _;- _;- _;- _;-
plant or bacteria infecting viruses are not.
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You go to visit a friend who has chickenpox. While visiting what are 2
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things you will be sure to avoid so that you don't also become infected?
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_;- You should keep a distance especially if your friend is coughing or
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sneezing because chickenpox can be transmitted through air-borne
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droplets. You should also avoid direct contact with the blisters of an
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infected individual. _;-
True or False. Although viruses may contain their genome within an
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enclosed space (much like the nucleus of a cell), it is considered neither
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eukaryotic nor prokaryotic. True _;- _;- _;-_;- _;-
Describe the two basic components of a virus.
_;- A virus has genomic
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material made up of either DNA or RNA and a capsid which is a
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protective structure that contains genetic material_;- _;- _;- _;- _;-
True or False. You would expect to see a viral envelope on a virus
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infecting a bacterial cell. False _;- _;- _;- _;-_;- _;-
,What type of microscope would be used to study the shape of a viral
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capsid? Due to its size (~30-150 nm) most viral capsids must be
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visualized via electron microscopy. _;- _;- _;-
How does the viral envelope both aid in cell entry as well as hide it
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from being detected by the immune system?
_;- It contains the
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proteins required for interaction with host cells. As the envelope is
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derived from the host cell, this camouflages the virus and makes it
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appear similar to the normal host cell.
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What must happen before viral replication of its genome can occur?
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The genome is replicated following attachment and entry
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Describe the basic steps of the viral life cycle.
_;- 1. Attachment: Viral
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receptors bind to host proteins on the surface of the cell.
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2. Entry: The virus fuses with the host membrane and enters the cell
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3. Uncoating: (where applicable) the viral capsid disassembles
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4. Replication: The viral genome provides the 'blueprint' to make copies
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of itself
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5. Exit: New viruses are produced and leave the cell
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6. New infection: Newly produced viruses leave the host cell and go on
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to infect new cells. The process outlined above now restarts.
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What is a bacteriophage?
_;- _;- _;- _;-_;- _;- A virus that infects bacteria
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, What structural aspects make bacteriophages distinct from viruses that
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infect either animals or plants?
_;- They have an icosahedral capsid
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head and a helical tail.
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Which viral replicative process results in the destruction of the host cell?
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_;- The lytic replication cycle
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Describe the appearance of a bacterial culture infected with virus at the
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time of infection versus later once viral replication is occurring at a high
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rate. It turns from a turbid to clear, the bacterial cell numbers
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decrease due to lysis and the media becomes clearer.
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To what family of viruses does rubella come from and how is it
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transmitted? Rubella comes from Togaviridae and it is transmitted
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by air-borne particles.
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What is the common name for rubeola, and is it a DNA or RNA virus?
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It is commonly known as measles and belongs to viruses called
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Paramyxovirus. It is a RNA. _;- _;- _;- _;-
What disease state emerges as a viral reactivation of a prior infection
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with the varicella virus?
_;- Shingles, also known as Herpes zoster, is
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due to the reactivation of the varicella-zoster virus (VZV). Because VZV
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lies dormant in inactive nerve cells, its reactivation typically results in
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painful blisters. However, unlike the initial chickenpox rash, the blisters
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are localized and limited to small areas.
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