structure of a virion
viral proteins surrounding the genome and nucleic acids sometimes surrounded by a membrane envelope
what virus structure is usually more stable
a naked virus without an envelope
virion structures / symmetry
helical symmetry
cubic symmetry
helical symmetry
rod shaped and of variable length
cubic symmetry
icosahedral/spherical
triangulation number
a measure of the size and complexity of an icosahedron based on the number of subunits
HIV capsid structure
isocosahedron with combination of 6 fold and 5 fold capsomeres
whats one limitation of icosahedral virions compared to helical virions
a helical virion can accommodate any size of genome, the rod just gets longer
icosahedral virions accomodate a limited genome size
what are virions held together by
weak, non covalent bonds
where can virions obtain envelopes (4)
nuclear membrane
ER
golgi
plasma membrane
what does type 1 and type 2 glycoproteins refer to
the orientation of it between the lumen of the ER and the outside of the cell
type 1 glycoprotein orientation
N terminus is is outside the cell
C terminus is inside
type 2 glycoprotein orientation
C terminus is outside the cell
N terminus is inside
where is a viruses envelope obtained from
cellular membranes derived from the host cell
what are the proteins between the nucleocapsid and envelope
tegument or matrix
why aren’t virions at their lowest energy state
if they were, they wouldn’t be able to undergo the conformational changes needed for infection
explain how virions are spring loaded
they sit at a stable state but not at their lowest energy state until they get a signal that induces an irreversible conformational change during attachment and entry
virions are ______
molecular machines that play an active role in delivering their nucleic acids into a cell
3 physical methods of determining the structure of a virus
electron microscopy
Cryo-EM
X-ray crystallography
what are the observed structures in electron microscopy
capsomeres
what does X ray crystallography need
good crystals otherwise the image won’t be clear or effective results
whats the modern way of looking at a virus
Cryo electron microscopy
