Introduction to Virology Flashcards
do viruses have a metabolic system of their own?
no
what cells do viruses infect?
prokaryotic cells or eukaryotic cells
what type of genome do viruses have?
DNA or RNA (unique in this)
what is the basic structure of a virus?
nucleic acid genome
protein coat
+/- envelope
what are the three basic types of capsid symmetry?
helical
icosahedral
complex
what virus families have complex symmetry?
bacteriophages
poxviruses
what is the structure of the rabies virus?
helical enveloped
what viruses have an icosahedral naked structure?
picornaviruses
polymaviruses
what viruses have an icosahedral enveloped structure?
herpesviruses
what does it mean for a virus to have an icosahedral structure?
isometric or cubic
what comprises the viral envelope?
lipid bilayer with protein
what may happen if many virions are released simultaneously?
integrity of host cell membrane may be compromised enough to lead to cell death
what are the two basic types of virus-encoded proteins?
structural and non-structural
what do structural proteins typically do?
capsid and genome packaging
what do nonstructural proteins primarily do?
enzymes: genome transcription, replication, and protein processing
if ssRNA serves as a message for translation (the same sense as mRNA), it is referred to as ____________________
positive-sense
if the viral RNA is antisense (or complementary) to that of mRNA- and thus cannot be translated directly- it is said to be ____________________
negative-sense
what are the steps to a virus attacking a host cell?
attachment
penetration
uncoating
multiplication
translation
assembly
release
what is important about viral genetics?
RNA polymerases typically lack error correction ability
viral antigens are important targets for immune response
where do DNA viruses usually replicate?
within the nucleus
where does the replication of most RNA viruses usually take place?
cytoplasm of cells
independent of nuclear machinery
how does the RNA of some animal viruses differ from others?
some have mRNA function and can be directly translated
others have antisense: must first be transcribed into RNAs by a viral-encoded RNA-dependent RNA polymerase
what are the general characteristics of viruses?
smaller than cells
some infect prokaryotic cells, some eukaryotic cells
simple and static structure; no metabolic system of their own
some destroy cells, others persist in latent or persistent state, other cause cellular malignant transformation
how do viruses exit the cell?
enveloped viruses exit via budding
naked virions exit by lysing or exocytosis from the host cell
