structure of viruses Flashcards
(11 cards)
what is a virus different genomes?
-what is a retorvirus genome
1) most viruses just contain RNA
2) retrovirus just contains ssRNA
(a virus can contain DNA or RNA but not both)
how do viruses encode the genes they express?
1)positive sense RNA genome
2) negative sense RNA genome
-message sense or anti-message sense
-how are proteins transcribed
-are they infecious
positive sense RNA genome:
message sense. and proteins can be transcribed directly. infectious
negative sense RNA genome:
anti- message snese must be transcribed into mRNA for protein translation to occur. non infectious.
difference between non segmented and segmented virus?
non segmented- single genome segment of DNA/ RNA
segmented- genome divided into 3 or more segments of RNA
what kind of proteins do viruses encode?
1) structural
2) non-structural
-are the proteins part of the viroin
structural= proteins incorporated into the viroin. essential for virus replication.
non-structural= proteins not part of the viroin
physical structure of a virus
-non- enveloped
-enveloped
and examples
non enveloped= ‘naked virus’ capside shell protects the genome e.g. dengue fever
enveloped= acquire a liquid bilayer e.g. contain spike proteins with viral glycoproteins.
function of glycoproteins in enveloped viruses?
allow virues to infect other cell by binding to receptors of cells
example of a virus with a complex structure?
bacteriophage T4
-virus that infect e.coli bacteria
definition of a viroin?
complete infecious form of virus outisde the host cell
1) when do enveloped virus require there envelope
2) key characteristics of non-enveloped (are they more stable)
1) from host cell membrane during budding
2) more stable in the environment e.g. adenovirus
The replication strategy of retroviruses, such as HIV
reverse transcription of RNA into DNA
function of
1) lytic cycle
2) lysogenic cycle
1) virus replicates rapidly and causes host cell lysis
2) result of viral integration of viral DNA into host genome
