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57 Cards in this Set
- Front
- Back
Viruses are obligatory _____________ parasites. |
intracellular |
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Host range refers to the spectrum of _______ ______ in which a virus can multiply |
host cells |
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_________ _________ is determined by the specific attachment site on the host cell’ssurface and the availability of host cellular factors. |
host range |
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Viruses range from 20 to 1000 ___ in length. |
nm |
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A ________ is a complete, fully developed viral particle composed of nucleic acidsurrounded by a coat |
virion |
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Viruses contain either ________ or _________, never both, and the nucleic acid may besingle- or double-stranded, linear or circular. |
DNA or RNA |
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The protein coat surrounding the nucleic acid of a virus is called the ____________. |
capsid |
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The capsid is composed of subunits, _______________, which can be a single type ofprotein or several types. |
capsomers |
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The capsid of some viruses is enclosed by an _________ consisting of lipids, proteins,and carbohydrates. |
envelope |
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Some envelopes have protein complexes embedded in their surface called __________. |
spikes |
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__________viruses (for example, Ebola virus) resemble long rods, and their capsids arehollow cylinders surrounding the nucleic acid. |
Helical |
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___________viruses (for example, adenovirus) are many-sided. Usually the capsid isan icosahedron. |
polyhedral |
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__________viruses have complex structures. For example, many bacteriophages have apolyhedral capsid with a helical tail attached. |
complex |
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______________ of viruses is based on type of nucleic acid, strategy for replication, andmorphology. a. Virus family names end in -_________; genus names end in -__________. b. A viral __________ is a group of viruses sharing the same genetic informationand ecological niche. |
Classification a. Virus family names end in -viridae; genus names end in -virus. b. A viral species is a group of viruses sharing the same genetic information and ecological niche. |
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Cultivation of some animal viruses requires whole ____________. |
animals |
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Some animal viruses can be cultivated in ___________ eggs. |
embryonated |
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______ __________ are cells growing in culture media in the laboratory. |
cell cultures |
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Viral growth can cause _________ _________in the cell culture |
cytopathic effects |
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______________tests are used most often to identify viruses. |
Serological |
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Viruses do not contain ____________ for energy production or protein synthesis. |
enzymes |
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For a virus to ___________, it must invade a host cell and direct the host’s metabolicmachinery to produce viral enzymes and components. |
multiply |
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During the _______ cycle, a phage causes the lysis and death of a host cell |
lytic |
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Some viruses can either cause lysis or have their DNA incorporated as a __________into the DNA of the host cell. The latter situation is called ______________. |
prophage; lysogeny |
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During the ____________ (attachment) phase of the lytic cycle, sites on the phage’s tailfibers attach to complementary receptor sites on the bacterial cell ______. |
adsorption; wall |
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During the ______________ phase, phage lysozyme opens a portion of the bacterial cellwall, the tail sheath contracts to force the tail core through the cell wall, and phage_______enters the bacterial cell. The phage __________ remains outside |
penetration; DNA; capsid |
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In biosynthesis, transcription of phage DNA produces ______ coding for proteins necessary for phage multiplication. |
mRNA coding |
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Phage _______ is replicated, and capsid proteins are produced. |
DNA |
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During __________, phage DNA and capsids are assembled into complete viruses |
maturation (assembly) |
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During __________, phage lysozyme breaks down the bacterial cell _______, and thenew phages are released. |
release; wall |
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During the __________ cycle, prophage genes are regulated by a repressor coded for bythe prophage. The prophage is replicated each time the cell divides |
lysogenic |
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Exposure to certain mutagens can lead to excision of the prophage and initiation of the_______ cycle. |
lytic |
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Because of lysogeny, lysogenic cells become immune to reinfection with the same phageand may undergo phage ___________. |
conversion |
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A lysogenic phage can transfer bacterial genes from one cell to another through______________. |
transduction |
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Animal viruses attach to the _________ __________ of the host cell. |
plasma membrane |
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Entry occurs by ______________ or ___________. |
endocytosis or fusion |
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Animal viruses are ______ by viral or host cell enzymes |
uncoated |
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The DNA of most DNA viruses is released into the _________ of the host cell.Replication and transcription of viral DNA produce viral ____ and viral _____. Capsidproteins are synthesized (translation) in the ____________ of the host cell. |
nucleus, DNA, RNA, cytoplasm |
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DNA viruses include members of the families ___, ____, ____, ____ and _____ |
Adenoviridae, Poxviridae, Herpesviridae, Papovaviridae, and Hepadnaviridae |
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Multiplication of RNA viruses occurs in the _________ of the host cell. |
cytoplasm |
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Retroviridae ___________ ___________ (RNA-dependent DNA polymerase) transcribesDNA from RNA |
reverse transcriptase |
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After maturation, viruses are released. One method of release (and envelope formation)is ___________. |
budding |
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Nonenveloped viruses are released through ruptures in the host cell membrane, (cell________). |
lysis |
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When activated, _______transform normal cells into cancerous cells. |
oncogenes |
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Viruses capable of producing tumors are called __________ viruses. |
oncogenic |
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The _________ material of oncogenic viruses becomes integrated into the host cell’s DNA. |
genetic |
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Oncogenic viruses are found among the Adenoviridae, Herpesviridae, Poxviridae,Papovaviridae, and Retroviridae |
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The Epstein-Barr Virus, a herpesvirus, causes _______ lymphoma and nasopharyngealcarcinoma. Hepadnavirus (HBV) causes _________ cancer |
Burkitt's; cervical |
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Among the RNA viruses, only ___________ seem to be oncogenic. |
retroviruses |
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_____ and _____ have been associated with human leukemia and lymphoma. |
HTLV-1 and HTLV-2 |
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The virus’s ability to produce tumors is related to the production of reverse transcriptase.The DNA synthesized from the viral RNA becomes incorporated as a _________ into thehost cell’s DNA. |
provirus |
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A provirus can remain latent, can produce viruses, or can ___________ the host cell. |
transform |
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A _________ viral infection is one in which the virus remains in the host cell for longperiods without producing an infection, examples are cold sores and shingles. |
latent |
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____________ viral infections are disease processes that occur over a long period andare generally fatal. |
Persistent |
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_________ are infectious proteins first discovered in the 1980s |
Prions |
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________diseases, such as CJD and mad cow disease, all involve the degeneration of________ tissue, the result of an altered protein; the cause can be a mutation or contact with an altered protein |
Prion; brain |
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Plant viruses must enter plant hosts through ________ or with invasive __________,such as insects. Some plant viruses also multiply in insect (vector) cells. |
wounds; parasites |
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_________ are infectious pieces of RNA that cause some plant diseases, such aspotato spindle tuber viroid disease. |
Viroids |