BIOC20 – Virology EXAM QUESTIONS WITH ANSWERS

BIOC20 – Virology EXAM QUESTIONS |\ |\ |\ |\ |\




WITH ANSWERS |\




Where can viruses spread - CORRECT ANSWERS ✔✔cell to
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cell and host to host, can spread across species barriers
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can infect all life forms
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What is DNA/ RNA needed for in a virus - CORRECT
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ANSWERS ✔✔- replication and expression of viral genome
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- packaging and delivery of the genome to more hosts
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- modifying host structure to enhance replication
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virion - CORRECT ANSWERS ✔✔complete virus particle
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outside the host cell |\ |\ |\




what essential functions do viruses lack - CORRECT
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ANSWERS ✔✔- synthesis of basic biological molecules
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- generation of ATP
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- protein synthesis machinery
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virion consists of - CORRECT ANSWERS ✔✔- nucleic acid
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genome

,- protective protein coat (capsid)
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- some may also have lipid envelope
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how do viruses release genetic material into host -
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CORRECT ANSWERS ✔✔inside host cells, virus particles
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disintegrate and release their genetic material. |\ |\ |\ |\ |\




major characteristics used for virus classification -
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CORRECT ANSWERS ✔✔- type of genome |\ |\ |\ |\ |\




- symmetry of capsid
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- presence or absence of an envelope
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- dimensions
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issues that arise with having an RNA genome - CORRECT
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ANSWERS ✔✔- mRNA must be synthesized from an RNA
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template
- RNA genome must be replicated
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do viruses encode their own RNA polymerases - CORRECT
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ANSWERS ✔✔Most of them do
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Retroviruses - CORRECT ANSWERS ✔✔have an RNA |\ |\ |\ |\ |\ |\ |\



genome which gets converted to DNA by the host cell
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using reverse transcriptase
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,the DNA copy is then inserted into the DNA of the host
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cell


how were viruses distinguished from other
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microorganisms - CORRECT ANSWERS ✔✔by filtration |\ |\ |\ |\ |\




first study to show that viruses exist - CORRECT
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ANSWERS ✔✔Tobacco Mosaic Virus |\ |\ |\




why are bacteriophages used as a model system for
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viruses - CORRECT ANSWERS ✔✔small simple and easy to
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grow
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use of plaque assay - CORRECT ANSWERS ✔✔to quantify
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viruses


how do plaque assays work - CORRECT ANSWERS ✔✔-
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phage binds to bacterial cells
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- replicates and releases progeny
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- repeated cycles lead to lysing of cells in the area
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surrounding infection |\




- observed as a clear plaque against uninfected cells
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, how are plaques counted - CORRECT ANSWERS ✔✔using
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plaque forming units |\ |\




what kind of eukaryotes are used in plaque assay -
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CORRECT ANSWERS ✔✔in vitro cultures of eukaryotes can
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be used
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how are eukaryotic plaque assays visualized and why -
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CORRECT ANSWERS ✔✔plaques are visualized by staining
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the cells, since dead cells dont stain well
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this needs to be done because eukaryotes grow in
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monolayers and therefore light doesnt get diffracted as |\ |\ |\ |\ |\ |\ |\ |\



much


why are RBCs used for assaying viruses - CORRECT
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ANSWERS ✔✔- visible due to color |\ |\ |\ |\ |\




- can be isolated and stored easily
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- have carbohydrate containing receptors on their
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surface, which allow animal viruses to bind |\ |\ |\ |\ |\ |\




hemagglutination assay - CORRECT ANSWERS ✔✔binding |\ |\ |\ |\ |\ |\



of excess virus which results in RBC agglutination
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(clumping)