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52 Cards in this Set
- Front
- Back
Virus
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Simple biomolecular particles with no metabolism,no growth, no cellular structure-
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CAPSID
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all viruses have...a protein coat surrounding the nucleic acid
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virus genome size
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2,500 to 250,000bp
10 nm - 300 nm |
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virus categorized by
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genome structure,sizes and shapes, presence of envilope
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Viral Host Range
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spectrum of host cells a virus can infect
Any one type of virus usually infects a specific set of cell types |
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cause of epidemics and pandemics
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nontypical viruses that can jump from species to species.
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Viruses can infect
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invertebrate, vertebrate, plant, protist, fungal or bacterial hosts.
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How does a virus attach
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Random encounter, Specific Receptors on surface of the host cell
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capsomere
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protein 1 or 2 viral-encoded subunits of capsid
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Envelope
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lipid bilayer with proteins & carbohydrates surrounding the capsid found in some viruses.
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Spikes
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glycoproteins Project from the envelope or capsid serve to bind to host.
Highly variable so as to evade host immune system |
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Helical
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viral shape: long rods
Ebola, rabies |
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Polyhedral
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viral shape:Many sided
Icosahedron – 20 faces most common adenovirus, poliovirus |
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Enveloped
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viral shape:helical or polyhedral
influenzavirus, herpes simplex virus |
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Complex
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Variety of more complicated structures
bacteriophage |
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Attachment
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1(adsorption)- virus attaches to receptor sites on cell
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Entry
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2
virus enters cell |
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Synthesis
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3
production of viral components |
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Assembly
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4
assembly of viral genomes, proteins, enzymes into mature progeny virions. (If the virus has an envelope, it is not complete until it buds through the cell membrane) |
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Release
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5
new virions exit host cell |
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T4 phage
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infects e coli, dsDNA genome
naked complex |
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virion
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viral particle
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phage plaques
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clear areas where bacteria have lysed due to infection
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Lysogenic Replication
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temperate, infect the cells but do not kill the cells
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prophage
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Viral/Phage DNA is incorporated into the host’s chromosome
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Lambda Phage
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Model Lysogenic Phage
Infects E. coli Linear dsDNA Naked, complex virus |
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Phage Conversion
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impact of lysogeny host cell may exhibit new properties +/-
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Transduction
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Phage inadvertantly packages bacterial DNA sequences along with viral DNA into its capsid
specialized or general |
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(+) strand RNA viruses
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virus encodes an enzyme to replicate the ssRNA genome then host directly translates the mRNA
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(-) strand RNA viruses
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RNA strand must function as template to make a complementary strand of + RNA before any translation can occur
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virion
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a completely developed, extracellular, infectious form of a virus
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virus
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intracellular parasite, meaning must operate within cell
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Influenza virus
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Enveloped, ssRNA, - strand, segmented
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HIV
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Enveloped, ssRNA, + strand, segmented)
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Herpes
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Enveloped, ds DNA virus
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hemagglutinin HA antigens
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surface protein designates flu strain many types
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neuraminidase NA antigens
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surface protein designates flu strain many types
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antigen
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a molecule that sometimes stimulates an immune response
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uncoating
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occurs when virus utilizes endcytosis
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antibodies
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prevent binding of virus
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Antigenic Drift: Minor
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caused by point mutations in the genes encoding hemagglutinin and neuraminidase. 2-3 year epidemics
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Antigenic Shift: Major
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caused by reassortment of RNA genome, causing virus to be recognized poorly by bodies defense (antibodies and T cells)
pandemics 10-50 years |
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retrovirus
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Copies RNA into double-stranded DNA
Degrades original viral RNA |
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Provirus
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Viral DNA incorporated into the host chromosome
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CD4
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receptor cell that hiv binds to.
present on surface of lymphocytes |
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HSV-1
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fever blisters, respiratory infections
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HSV-2
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genital infections
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Varicella Zoster Virus
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herpes. chicken pox
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PRIONS
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Proteinaceous infectious particle, only a protein
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PrPc
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normal
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PrPSc
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acquires a different shape/conformation than normal form, alters proteins function, infectious!
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VIROID
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Does not code for a protein, causes plant disease.
May have evolved from introns |