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29 Cards in this Set
- Front
- Back
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Budding
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viral envelops acquired at cellular membrane are aquired by __________
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capsid
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rigid, symmetrical, containers
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core proteins
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protein that condensed viral DNA by neutralizing the negative charges of the phosphate groups
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cryoelectron microscopy
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method of freezing viron that holds preservation of structure with poor contrast
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ectodomain
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large glycosylated external domain
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envelope
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lipid bilayer membrane that encloses the capside
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genetic economy
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large need for protein capsid from small genome
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helical symmetry
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elongated tube of identical subunits along helical axis
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icosahedral symmetry
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includes exactly 60 subunits
has 5, 3, 2 fold symmetry |
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negative staining
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reveals structure of virion by exclusion of e- absorbing molecules such as uranyl acetate
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nucleocapsid
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capsid that contains viral genome
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quasiequivalent
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results from nonequivalent interactions betwee identical subunits
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signal sequence
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Type 1 membrane proteins that have signal sequence cleaved from N terminusas they are inserted into the endoplasmic reticulum during synthesis.
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triangulation number
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multiples of 60 that lead to quasiequivalent structures. T= h2 + hk + k2
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virion
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Complete infectious virus particle
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symmetry
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correspondence in size form and arrangement of parts around a point or line or plane
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Icosahedral symmetry is selected because
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requires little coding capacity
2)allows self assembly with little energy expended |
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Icosahedrals have _____ faces, and ______ vertices
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20 faces
12 vertices |
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capsid with 60 subunits with equivalent interactions
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icosahedral
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capsid with >60 subunits
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quasi equivalent
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capsomeres
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protomers/protein subunits
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T=1 capsid contains
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12 pentameric capsomeres
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icosahedral capsid properties
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1) rotational symmetry
2) 5:3:2 rotational symmetry 3) triangulation number |
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Triangulation number
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1)describes # of subunits in icosahedron
2) the number of subtriangleson a single face of icosahedron when each capsomere is connected by a line. |
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Helicohedral + examples
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Helical capsid
Tobacco Mosaic Influenza |
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capsid size does/does not depend on T number
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Does not
ie fewer subunits may be larger |
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P number
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1)distance between 2 adjacent helices of a helical capsid
2)= #of units per turn X axial rise per unit. ie 16 1/3 subunits per turn/1.4 A/subunit = 23 A |
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3rd type of capsid type
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complex
ie pox virus |
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Pox virus capsid characteristics
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lipid protein envelope atypical, insensitive to soaps
stable in nature, can pick up from surgaces |
