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60 Cards in this Set
- Front
- Back
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name: extracellular form of the virus
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virus particle OR virion
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what surrounds viral genome?
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capsid
sometimes lipid-bilayer envelope |
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t/f: viruses replicate within the host
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t
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t/f: viruses adapt within the host
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t
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t/f: viruses are obligate intracellular parasites
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t
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t/f: measles, mumps, common cold are diseases caused by viruses
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t
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give 3 viral enzymes used as molecular biology tools
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DNA ligase
reverse transcriptase RNA polymerases RNase H |
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what sets viruses apart from cells in terms of genome replication?
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they can use RNA as a genome, or use ssDNA as a genome
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what are viruses used for in the context of gene therapy?
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to xfer genes into cells
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size range of viruses
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28nm (poliovirus) - 200nm (smallpox)
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why does it make sense for capsids to be formed from many copies of the same protein?
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limited size => limited genome coding capacity
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name: protein coat directly surrounding genome
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capsid
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what is the nucleocapsid?
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the nucleic acid and capsid complex
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name: lipid bilayer and associated glycoproteins surrounding many types of nucleocapsids
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envelope
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name: the entire virus particle
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virion
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t/f: DNA and RNA are sometimes found together within the virus capsid
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f
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where does the virus envelope come from?
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previous host
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what are the three viral morphologies?
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helical, spherical, complex
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what shape are 'spherical' viruses technically?
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icosahedron
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t/f: some viruses contain a genome and enzymes within the capsid
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t - may need enzymes to initiate replication cycle
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t/f: viruses are capable of reproduction
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f - the term replication is used because of the host dependency
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length of typical animal virus replication cycle
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8-24hr
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name: the receptor on the virus used for attachment
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anti-receptor
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name: the receptor on the host cell that the virus binds to
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virus receptor
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what two factors determine host range?
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presence of a viable receptor (susceptible)
presence of proper intracellular factors (permissive) |
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cell types that a virus can infect (enter) are ___
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susceptible
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cell types that a virus can replicate in are ___
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permissive
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t/f: virus attachment is energy dependent
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f
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t/f: virus entry is energy dependent
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t
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define: (+) strand RNA
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RNA that is immediately translatable (functionally equivalent to mRNA)
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t/f: the (+) and (-) strands are complementary
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t
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t/f: some viruses contain segmented genomes (several molecules of RNA)
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t
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In eukaryotic cells, where are the DNA and RNA polymerases located?
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nucleus
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Eukaryotic mRNAS are modified with a ___ cap at the 5' end and a ___ tail at the 3' end. Why is this a problem for viruses?
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methylated guanine, poly-A
this is a problem because many viral mRNAs lack these structures and must out-compete cellular mRNA for translation |
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t/f: virus assembly is an energetically unfavorable process
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f
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t/f: capsid assembly relies on inherent protein affinities
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t
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RNA-dependent RNA polymerases do what?
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synthesize the complementary strand of RNA using viral RNA as template
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t/f: all DNA viruses use the host DNA polymerase to replicate thier viral DNA
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f - some provide thier own DNA polymerases
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define retrovirus
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RNA virus that uses reverse transcriptase to synthesize a single strand
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name: virus release
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egress
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what are the possible ways for virus to leave the cell?
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cell lysis
budding |
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t/f: cell lysis is used by enveloped viruses
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f
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most non-enveloped viruses leave the cell by ___
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lysis
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enveloped viruses leave the cell by ___
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budding
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during budding, what three places can the virus acquire an envelope from?
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as it extrudes out of nucleus
OR intracellular vesicle OR plasma membrane |
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t/f: budding is always harmful to the cell
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f
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t/f: all enveloped viruses modify the lipid envelope by inserting viral proteins
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t
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t/f: all virions must enzymatically cleave structures on the cell to free themselves during egress
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f - only some (ie influenza)
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enveloped viruses modify the envelope by inserting viral proteins during egress. What are these used for?
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attachment
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what four characteristics are used in the 'classic' classification system for viruses?
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nature of nucleic acid
symmetry of capsid presence of envelope dimensions of virion / capsid |
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t/f: type of disease a virus caused is used to classify viruses
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f
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how does the Baltimore system classify viruses?
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based on the genetic system of each virus, and the relation between genome and production of mRNA
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t/f: the classical and Baltimore system are mutually exclusive
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f
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t/f: studies of viral replication require the growth (cultivation) of host cells
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t
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what are the two types of cell culture?
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primary
tumor |
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to make a primary cell culture, animal tissue is treated with ___ to dissociate the cells
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trypsin
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t/f: primary cell culture is immortal
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f - after only a few rounds of division they will die
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define 'in vitro'
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in glass (test tube)
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define 'in vivo'
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in the body
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What four viruses have been linked to cancer?
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Epstein-Barr -> Burkitt's lymphoma (tumor of jaw and abdomen)
Hepatitis B (some liver cancers) Papillomaviruses (cervical cancer in women) two retrovirus (HTLV-1 and -2: T cell leukemia) |
