Term
| What makes viruses obligate intracellular parasites? |
|
Definition
| they can only replicate inside a living host cell, taking advantage of the host cell's metabolic machinery |
|
|
Term
| Name and describe the 3 components that make up viruses. |
|
Definition
1) nucleic acid core-DNA or RNA, can be ss, ds, circular, linear, or segmented
2) capsid-protein coat surrounding nucleic acid, protects and determines shape of virus, made of capsomeres
3) envelope-not all viruses have, bilayer surrounding the capsid, may have spikes, helps cells "hide" from immune system but cannot withstand extreme conditions |
|
|
Term
| Name and describe the different viral shapes (determined by capsid). |
|
Definition
helical-ribbon-like protein that forms spiral around nucleic acid
polyhedral-many sided
icosahedral-one of most common polyhedral capsid shapes, 20 triangular faces
complex-combo of helical and polyhedral
sperical
filamentous-thread like in shape |
|
|
Term
| host range vs. viral specifity |
|
Definition
host range-spectrum of hosts that a virus can infect
viral specifity-specific kinds of cells a virus infects, determined by specific receptors on host & enzymes required by virus |
|
|
Term
| Describe how viruses are classified and named into families, genus, and species. |
|
Definition
1) Family-distinguished first on basis of n.a. type, capsid symmetry, envelope, and size, names all end in viridae
2) genus-names all end in virus
3) species-names are common English words |
|
|
Term
| positive sense RNA vs. negative sense RNA |
|
Definition
positive sense- RNA strand that encodes information for making proteins needed by a virus, RNA acts like mRNA & can be translated by host's ribosomes
2) negative sense RNA-RNA strand made up of bases complementary to lose of a positive sense RNA, must be a template during transcription to make complimentary positive sense RNA |
|
|
Term
| What are the 4 (+) sense RNA families? |
|
Definition
| Picornaviridae, Togaviridae, Flaviviridae, Retroviridae |
|
|
Term
| What are the 7 (-) sense RNA viruses? |
|
Definition
| Paramyxoviridae, Rhabdoviridae, Orthomyxoviridae, Filoviridae, Bunyaviridae, Arenaviridae, Reoviridae |
|
|
Term
| Name the DNA virus families. |
|
Definition
| Adenoviridae, Herpesviridae, Poxyviridae, Papovaviridae, Hepadnaviridae, Parvoviridae |
|
|
Term
|
Definition
| viruses that were previously endemic or had "cross-species barriers" and expanded their host range to other species |
|
|
Term
|
Definition
reservoirs-animals that can harbor the disease and can be negatively effected by it
vectors-animals that carry and transmit the disease without being harmed by it
Ex. mosquitoes, flies, ticks, etc |
|
|
Term
|
Definition
| use of highly specific viruses that attach only targeted bacteria and leave beneficial bacteria |
|
|
Term
| What are the 5 cycles in the replication of a phage or virus? |
|
Definition
1) adsorption-attachment of viruses to host
2) penetration-entry of virions or genome into host
3) synthesis-synthesis of new n.a. capsids, and other components by using metabolic machinery of host
4) maturation-assembly of new components into complete virions
5) release-departure of new virions from host, lyse host cell |
|
|
Term
| What are the 3 kinds of viral-host cell interactions? |
|
Definition
1) productive infection-results in cell lysis
2) persistent infection-virus often buds from cell without killing it
3) latent infection-viral n.a. is integrated into host, virus becomes dormant, does not reproduce until triggered, enters lytic cycle |
|
|
Term
|
Definition
| description of viral growth (biosynthesis and maturation) based on observations of phage-infected bacteria in laboratory cultures |
|
|
Term
|
Definition
| period during replication in which viruses have adsorbed to and penetrated host cells but cannot yet be detected |
|
|
Term
|
Definition
| period of bacteriophage growth curve that spans the time from penetration through biosynthesis |
|
|
Term
|
Definition
| viral assay used to determine viral yield by culturing viruses on bacterial lawn and counting plaques |
|
|
Term
|
Definition
| cells that attach to surfaces, multiply, and spread to from sheets one cell thick |
|
|
Term
|
Definition
| transferred to new containers w/fresh medium |
|
|
Term
|
Definition
| come directly from the animal and are not subcultured, limited # of transfers, if subcultured cell strain results |
|
|
Term
|
Definition
| dominant cell type resulting from subculturing |
|
|
Term
| diploid fibroblast strains |
|
Definition
most widely used cell strains
derived from fetal tissues that retain fetal capacity for rapid repeated cell division |
|
|
Term
|
Definition
cells that reproduce for an extended number of generations, unlimited life,
Ex. HeLa cell line |
|
|
Term
|
Definition
| visible effect viruses have on cells |
|
|
Term
|
Definition
| induction of defects during embryonic development |
|
|
Term
|
Definition
| drug or other agent that induces defects, viruses can be teratogens |
|
|
Term
|
Definition
| blood test to identify teratogenic diseases in pregnant women and children |
|
|
Term
|
Definition
| small, mRNA molecules which lack genes needed for replication, can replicate only in presence of helper virus |
|
|
Term
|
Definition
| infectious RNA particle w/o protein coat, smaller than a virus, causes plant diseases |
|
|
Term
|
Definition
| small proteinaceous infectious particle, causes at least 8 progressive neurological diseases |
|
|
Term
| What is the only thing that can destroy prions? |
|
Definition
|
|
Term
|
Definition
| tumor, localized accumulation of cells |
|
|
Term
|
Definition
| cancer-causing genes, cause uncontrollable cell division |
|
|
Term
|
Definition
| normal gene that when under the control of a virus can cause uncontrolled cell division |
|
|
