viruses Flashcards
in which direction does positive sense viral RNA go?
5’-3’
in which direction does negative sense viral RNA go?
3’-5’
what implication does the polarity of negative sense viral RNA have?
a positive RNA must be produced from an RNA-dependent RNA polymerase prior to translation
what is meant by monocistronic?
mRNA that can only encode for one polypeptide per RNA molecule
what is an issue with for DNA viruses entering eukaryotes?
eukaryotes can only translate monocistronic messages, viruses are polycistronic
how do viruses overcome the necessity for a monocistronic message?
- making a cleavable polyprotein
- have a different message for each protein
- make sure there are internal initiation sites
why is +ve sense vRNA directly infectious?
it has the same polarity as mRNA
what is meant by the term ‘directly infectious’?
does not require viral proteins for infection
what is meant by subgenomic monocistronic mRNAs when referring to calicivirus?
the virus makes 3 different mRNAs for all 3 proteins by differential splicing of one pre-mRNA strand
what is a polyprotein?
a large protein that is cleaved into separate smaller proteins with different biological functions
what is the purpose of a double stranded replicative intermediate in negative sense viral RNA?
a template for further replication
what is the difference between segmented and multipartite genomes?
segmented genomes have 2 or more pieces of nucleic acid in the same particle whereas multipartite contains each segment in a different particle
