24. Properties of viruses Flashcards
enveloped viruses are disrupted by ___
acid
detergents
drying
heat
what are the morphological groups of viruses?
- naked icosahedral
- enveloped icosahedral
- naked helical
- enveloped helical
- complex
viruses are only visible under a __
electron microscope
how do you cultivate viruses?
living host cells
and enveloped virus is released by:
budding and cell lysis
cell lines
diploid, 50-70 passages
what happens to viral genomes of DNA viruses?
they remain in the infected cell, most reside in the nucleus (except pox viruses)
a naked capsid is stable to
- temperature
- acid
- proteases
- detergents
- drying
eclipse period
time from first infection to intracellular virus
almost all viruses contain either __ or __ with the exception of __
DNA, RNA, CMV
steps in viral replication
- recognition
- attachment and penetration
- uncoating
- macromolecular synthesis
- early mRNA codes for non-structural proteins
- late mRNA codes for structural proteins
- posttranslational modification of proteins
- assembly of viral components
- budding of enveloped viruses
- release of virus
can cells replicate RNA?
no, RNA viruses must encode an RNA-dependent RNA polymerase
most RNA viruses replicate in __
the cytoplasm
enveloped virus components:
membrane
lipids
proteins
glycoproteins
viruses that don’t use the cell polymerase __
carry their own polymerase
positive vs. negative strand RNA
positive- can be directly transcribed into a protein
negative- has to be transcribed by an enzyme into a positive strand
what enzymes do viruses have for energy metabolism?
none
established cell lines
heteroploid, continuous passage in vitro
what do DNA polymerases require in order to replicate the viral genome?
a primer
early genes tend to encode:
DNA-binding proteins
late genes encode:
structural proteins
structure of a virus
genome in a protective protein shell, capsid shell may be enclosed within an envelope that contains both protein and lipid
naked helical viruses only exist in __
plants
primary cell culture
diploid, 1-2 passages, taken from living things
