Lecture 3 CSB351 Virology

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Department
Cell and Systems Biology
Course
CSB351Y1
Professor
Mounir Abou Haidar
Semester
Fall

Description
Lecture3 September-22-09 11:33PM { Virusislikeakeyfittingalock(cell)-->virusisspecificfortargetcells { Virushasitsownglycoproteinattachedtoit { Onlyforenvelopedvirus:Envelopeofvirus:fuseswithmembraneofcell,virusgetsin { Virusreplicatesonceinsidethecell-->replicationdependsontypeof virus: +RNA:RNAdirectlytranslatablebyribosome:riboseesmRNAofthevirus,bindstothis,translatesit-->convertsintoprotein(AUG=start protein,methionine)-->1stRNAtranslated:makespolymeraseenzyme(whichwillgoandcopyoutthousandsofviralRNA) ThelargemajorityofDNAviruses:replicateinthenucleusofthecell(thisiswhereDNAchromosomesare,andwhereDNA-dependent RNApolymerasesare-->functionistosynthesizemRNA) ALLDNAVIRUS (exceptforVACINEA?)replicateinthenucleus-->Gointhere,usemachineryofcelltomakemRNAfromDNA-->mRNAgoes intocytoplasmtobetranslatedintoviralprotein MostDNAvirusesdontcodefortheirownDNA-dependentRNApolymerase,becausetheyknowthatthecellhasthemforitsown functions ALLRNAviruses:dont go intonucleus 1exception:Influenzavirus-->gotonucleusforreplication Influenzaviruswantstomakemachineryofthecellitsslave!-->virusgoesintonucleus,cutsoffcapregionofmRNAofthecell,putthem ontheirownmRNA-->stealstheircaps!(OtherRNAviruses:polymerasesynthesizetheirowncaps) Double-edgedsword:cellsownmRNAsdestroyedsocannotmakeitsownprotein,whilelotsofInfluenzavirusisbeingproduced Replication 1. Recognitionoftargetcell 2. Attachment 3. Penetration 4. Uncoating 5. Macromolecularsynthesis: EarlymRNA& non-structuralproteinsynthesisgenesforenzymesandnucleicacid-bindingproteins Replicationofgenome:viralRNADNA LatemRNAand structural proteinsynthesis(virusfirstneedstocopylotsofRNADNA) Posttranslationalmodificationofprotein(i.e.Glycoproteins-->havesugarsaddedtothem)-->Onceyouputsugarona protein= puttingzipcodeonletter-->shipsfromGolgioutto themembraneofthecell Virusesknowhowtousethisfortheirownadvantage 6. Assembly:Afewhoursafterinfection:producetonsofnucleicacid-->packaged-->havevirusassembly-->Lysisandreleaseofvirusfrom cells 7. Releaseofvirusfromcell:somebud(envelopedvirus)somelyse: destroysthecells(i.e.Cholera-->waterydiarrhoea) (2)Page 6 Consequences of virus replication Disease { Whenvirusmultiplies,usescellma
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