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40 Cards in this Set
- Front
- Back
Viruses (def and classificiation)
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obligate intracellular parasites- not cells have no nuclues oganelles, not living things
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virion
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complete virus particle----consists of a molecule of DNA or RNA enclosed in coat of protein called capsid
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3 possible Hosts for animal viruses
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the right animal (suitable/ species), embryonated eggs, tissue (cell) cultures -in monolayers of cells or plaques localized area)
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embryonated egg process
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want a living embryo, insert virus into chorioallantoic membrane
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polio virus
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grows using plaques, john ender developed the culture method, jonas saulk vaccine
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Hosts for bacteriophages
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usually cultivated in broth or agar cultures of suitable, young, actively growing bacteria
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Plaques
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area of dead cells on plate where does virus form--on plaque directly
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hosts for plant viruses
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plant tissue cultures: necrotic lesions (dead regions) (can happen genetically or infection--ex tulip white plant pattern) plant protoplast culture
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Main structural components of a virus
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nucleocapsid, capsid, envelope (some)
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nucleocapsid
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nucleic acid held w/in protein coat
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capsid of a virus
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protein coat surrounding viral genome, protects genome, aids in transfer, protomers/capsomers (fingers on hand if hand is capsid) are protein subunits making up a capsid
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viron's envelope
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some virions have an envelope enclosing capsid, spikes on outer membrane usually enzymes--hijack host membrane, have nucleic acid core
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morphological types of viruses
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polyomavirus --(a bunch of diamonds) icosahedral, helical, complex, envelopes, tubulovirus
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herpes virus is a morpholical example of
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envelope with polyomavirus inside
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Helical Capsids
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has RNA twisting in strand up and shapped like hollow tubes with protein walls
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icosahedral capsids
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regular polyhedron with 20 eauilateral triangular faces
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Influenza virus strains (bird and swine numbers) tamiflu inhibits, host options, ID
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bird h5n1, swine h1n1, tamiflue inhibts neuraminidase, birds, pigs, humans, ID by proteins on diff strains and variable Amino acids, usually can't cross species, some with mixed genetic info can
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Viruses with Capsids of Complex Symmetry
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Binal symmetry –
having both icosahedral and helical symmetry |
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Classification of Bacteriophages based on 2 criteria
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morphology and nucleic acid properties
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What are the major phage families ang genera based on for classification
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genetic info: 2 types: DNA RNA (dsDNA, ssDNA, ssRNA, dsRNA)
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Reproduction of Double stranded DNA phages is known as
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Lytic sycle
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Lytic cylce def
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phage life cycle that culminates with host cell bursting, releasing virions
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attachement/aka adsorption in the lytic cycle
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where specific coding comes into pay. receptor sites specific surfae for each virus, can be proteins, lipopolysaccharides, techpic acids
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lytic cycle
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dna injection into host cell, early mRNA made and host dna degraded, phage dna made, late RNA made heads and tails made, heads of virons filled, virons formed, host cell lysis (what kills host cell). host cell zombie like not cellular genetic info remains
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synthesis of phage nucleic acids and proteins
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sequential: early mRNA synthesis, synthesis of proteins that enable t4 to take over host cell, phage dna replication, late mRNA synthesis--encoding capsid proteins and others for assembly
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Temperate Bacteriophages and Lysogeny def
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nonlytic (infect but not kill) relationship between a phage and its host (host cell can still reproduce)
usually involves integration of phage genome into host DNA |
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temperate phages
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phages able to establish lysogeny, the type of phage that can do lysogeny: temperate virus
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Lysogenic conversion
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change in host phenotype induced by lysogeny: making a bacteria that's usually not harmful into a lysogen
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Bacteria that undergo lysogenic conversion
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salmonella modifed, corynebacterium diphtheriae---toxin genes in the temperate phage ---diphtheria toxin
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does the lytic cycle occur in lysogens
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yes, has to occur in order for them to reproduce
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Classification of Animal viruses most important criteria
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morphology nucleic acid properties genetic relatedness---determined by numerous techniques, including sequencing data and nucleic acid hybridization
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classification by 4 combination potentials
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single, double, enveloped, or naked.. then capsid symmetry important
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RNA viruses classification
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double, single, negative possitive. possitive (5-3 prime) and negative (3-5 prime)
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reproductive process of animal viruses
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similar to bacteriophages--lytic lysogenic states, steps: adsorption, penetration and uncoating, replication of virus nucleic acids, synthesis and assembly of virions, release
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Humans are/ aren't lysogenic
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humans are walking lysogens ex: chicken pox, shingles (cell never being able to get rid of genetic info still in our cells)
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adsorption of virions
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specific protein and enzyme surface receptros in spec host
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Penetration and Uncoating
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one of two mechanisms used by most viruses fusion of envelope with host membrane
endocytosis in some cases only nucleic acid enters host cell |
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HIV virus facts
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immune cells (T-helper cells) CD4 protein recognized with bonding and specific attachment, CCRS receptors, and macrophage all get infected, so weakens and hijakes immune system cells
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process of endocytosis
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enveloping virus, creates double cell membrane by host and vesicle and absorption, naked part of virus comes out and release genetic info in capsid form
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endocytosis for nake virus
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same idea as enveloped one just no double membrande
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