L18 Symmetry, genome, shape and size Flashcards
what are viruses?
acellular microorganisms that require a host to survive
obligate intracellular parasites
aspects of viruses that make them living
have self-replicating genome
produce offspring
encode enzymes
what does a viruses ability to encode enzymes do
allows it to manipulate the metabolism of the host
what aspects of viruses make it non-living
acellular
obligatory dependence on host
do not have their own metabolism
what aspects of viruses make it non-living
acellular
obligatory dependence on host
do not have their own metabolism
general structure of a virion
nucleocapsid (nucleic acid genome + protein coat)
name of the protein coat
capsid
what is the third components that is sometimes present in virions
lipid envelope
what is the capsid comprised of
multiple units of protein building blocks
-protomers
symmetry of protomers
helical
icosahedral
complex
describe a helical structure
a helix (spring) similar to the nucleic acid
example of virus with helical symmetry
tobacco mosaic virus
examples of enveloped helical viruses
influenza
covid
describe icosahedral symmetry
icosahedral (20 face polyhedron)
each face is an equilateral triangle
what happen within each triangular face of viruses with icosahedral symmetry
protomers further arrange into units of 5-6 to form capsomers