Unformatted text preview: Questions and Answers – Viruses Part 2
1. You have isolated a virus that infects eukaryotic cells and has a single ssRNA(-) genome.
You find that one of the viral proteins is similar at the amino acid sequence level to other
characterized proteins with endonuclease activity. Propose one hypothesis for what function
this putative endonuclease could serve for the virus. 2. You have identified a virus that has a ssRNA genome. You want to know whether this viral
genome is an ssRNA(+) genome or a ssRNA(-) genome. You have a preparation of pure viral
particles (i.e. no cellular material) that you have broken open. What would you look for in these
viral particles that would lend support for the genome being (+) or (-) stranded? 3. You have identified the viral proteins produced in a mammalian cell infected by a (-) ssRNA
virus. Two of the proteins are identical in their N-terminal 200 amino acids, but completely
different at the 100 C-terminal amino acids. Given what you know about gene expression by
other RNA viruses, speculate as to the most likely mechanism that the virus gives rise to these
two proteins. 4. You determine that a newly discovered (+) ssRNA virus of mammalian cells has a genome
with a protein covalently attached to the 5’ end. Given what you know of other RNA viruses,
speculate as to the most likely function of the 5’-attached protein. 5. Describe a mechanism by which prokaryotic (+)ssRNA viruses can achieve higher levels of
coat protein synthesis relative to RNA-dependent, RNA polymerase (RDRP) synthesis. ...
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