November 23 Lecture Notes

November 23, 2009

Flu virus is an RNA virus which is not a retro virus
• RNA copied by RNA replicase; enzyme made by virus, copies RNA- RNA copies
• Single stranded RNA genome translated by host ribosomes and transfer RNA amino acids by host cells rRNA, tRNA amino acids
E)Assembly of new virions:
* when viral genes have been expressed ( i.e. proteins coded fro by genes have been made), viral particles spontaneously form
*( capsomeres aggregate around viral genetic material, glycoproteins collect on capsomeres
F) i) cell just dies the virus contains an enzyme that lyses the cell or kills it in its entirety
- lysis of host cell: cell destroyed, this frees viral particles to infect new cells
Ex. T4 phages
ii) Budding : Virion uses glycoproteins to grab onto host cell membrane, wrap self in membrane and yank itself away – most common way of releasing virions in eukaryotic host cells
V. Consequences of Viral Infection on the Host Cell
a). death of cell:
*cell directly lysed by virus
* cell dies not directly bc of virus
* ex. Our immune system kills the cell b/c virally-infected
* viral replication taxes cell function seriously enough that cell dies
b). Disruption of cell function
*cell alive, but unable to do much more than make virions
c) transformation of normal cell to cancer cell
-change of genetic function of a cell from having once set of genetic characteristics to another set of genetic characteristics (transformation)
- ex. HPV 16 and 18 – infect epithelial cells integrate own DNA into host cell DNA
* knocks out apoptosis in infected cells
*Result: makes cell cancerous
a) Animal cells/ cell culture
* must grow viruses in appropriate host cell (grown in small flasks)

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