viruses, part 2. bacteriophage multiplication lytic cycle –ends with cell lysis –death of host...

Viruses, part 2Viruses, part 2

Bacteriophage MultiplicationBacteriophage MultiplicationLytic CycleLytic Cycle– Ends with Cell lysisEnds with Cell lysis– Death of host cellDeath of host cell

Lysogenic CycleLysogenic Cycle– Viral Genome integrates into host chromosomeViral Genome integrates into host chromosome

Prophage viral DNAProphage viral DNA

Lytic and lysogenic Cycle:Lytic and lysogenic Cycle:– AttachmentAttachment

Phage attaches by Phage attaches by tail fibers to host tail fibers to host cellcell

– PenetrationPenetrationPhage lysozyme Phage lysozyme opens cell wallopens cell wallDNA is injected DNA is injected into cellinto cell

– BiosynthesisBiosynthesisReplicate viral Replicate viral DNADNAMake viral proteinsMake viral proteins

– MaturationMaturationAssemble new Assemble new virus particlesvirus particles

– ReleaseReleasePhage lysozyme Phage lysozyme breaks cell wallbreaks cell wallNew virions are New virions are releasedreleased

IntegrationViral DNA becomes prophage

Cell divides like normal replicating prophage DNA while it reproduces

Virus MultiplicationVirus Multiplication

AttachmentAttachment

PenetrationPenetration

(Uncoating)(Uncoating)

BiosynthesisBiosynthesis

MaturationMaturation– Putting the virus Putting the virus

together together

ReleaseRelease

Animal virus Animal virus attachment/penetrationattachment/penetration

Naked virusNaked virus– No envelopeNo envelope– Binds to surface of host cell and injects its DNA Binds to surface of host cell and injects its DNA

(similar to bacteriophage)(similar to bacteriophage)

Envelope virusEnvelope virus– Membrane fusionMembrane fusion– Binds to receptors and envelope fuses with the host Binds to receptors and envelope fuses with the host

membranemembrane

Envelope virusEnvelope virus– PhagocytosisPhagocytosis– Virus particles taken in by endocytosisVirus particles taken in by endocytosis

Animal Virus MultiplicationAnimal Virus Multiplication



UncoatingUncoating


MaturationMaturation– Putting the virus together Putting the virus together

ReleaseRelease

Biosynthesis and maturationBiosynthesis and maturation

Single stranded DNASingle stranded DNA– DNA enters the nucleusDNA enters the nucleus– First produce ds DNA in nucleusFirst produce ds DNA in nucleus– Replication – make more DNAReplication – make more DNA– Transcription in nucleus – make RNATranscription in nucleus – make RNA– Proteins made in the cytoplasm from mRNAProteins made in the cytoplasm from mRNA– Proteins transported to the nucleusProteins transported to the nucleus– Viruses Viruses assembledassembled in the nucleus with single in the nucleus with single

stranded DNAstranded DNA


Double stranded DNADouble stranded DNA– DNA enters the nucleusDNA enters the nucleus– Replication and transcription in the nucleusReplication and transcription in the nucleus– Proteins made in the cytoplasm from mRNAProteins made in the cytoplasm from mRNA– Proteins transported into the nucleusProteins transported into the nucleus– Assembly of virus in the nucleus with dsDNAAssembly of virus in the nucleus with dsDNA


+ strand RNA (sense RNA)+ strand RNA (sense RNA)– Entry and stay in the cytoplasmEntry and stay in the cytoplasm– Make – strand RNA with Make – strand RNA with RNA dependent RNA dependent

RNA polymeraseRNA polymerase– - strand RNA serves as template for more + - strand RNA serves as template for more +

strand RNAstrand RNA– + strand RNA serves as mRNA+ strand RNA serves as mRNA– Makes mRNA in the cytoplasmMakes mRNA in the cytoplasm– Assembly in the cytoplasmAssembly in the cytoplasm

Packaged with RNA dependent RNA polymerasePackaged with RNA dependent RNA polymerase


- Strand RNA (antisense RNA)- Strand RNA (antisense RNA)– Entry and stay in the cytoplasmEntry and stay in the cytoplasm– Make + strand RNA with Make + strand RNA with RNA dependent RNA dependent

RNA polymeraseRNA polymerase– + strand RNA serves as mRNA and makes + strand RNA serves as mRNA and makes

viral proteins in the cytoplasmviral proteins in the cytoplasm– + strand also serves as a template to make – + strand also serves as a template to make –

strand RNAstrand RNA– Assembly of virus in the cytoplasmAssembly of virus in the cytoplasm



Double stranded RNADouble stranded RNA– Entry and stay in the cytoplasmEntry and stay in the cytoplasm– + strand RNA serves as mRNA and makes + strand RNA serves as mRNA and makes

viral proteins in the cytoplasmviral proteins in the cytoplasm– Makes RNA dependent RNA polymerase Makes RNA dependent RNA polymerase – + strand also serves as a template to make – + strand also serves as a template to make –

strand RNAstrand RNA– - strand serves as a template to make + - strand serves as a template to make +

strand RNAstrand RNA– Assembly of virus in the cytoplasmAssembly of virus in the cytoplasm



Retroviruses Retroviruses – + strand RNA viruses+ strand RNA viruses– Reverse transcriptaseReverse transcriptase makes DNA from RNA in the makes DNA from RNA in the

cytoplasmcytoplasm– Then DNA moves to the nucleusThen DNA moves to the nucleus– (negative) Single strand DNA enters the nucleus and (negative) Single strand DNA enters the nucleus and

makes double stranded DNAmakes double stranded DNA– DNA makes mRNA in the nucleusDNA makes mRNA in the nucleus– RNA makes viral proteins in the cytoplasmRNA makes viral proteins in the cytoplasm– Assembly in the cytoplasmAssembly in the cytoplasm

Reverse transcriptase packaged with the virusReverse transcriptase packaged with the virus




UncoatingUncoating


MaturationMaturation– Putting the virus together Putting the virus together

ReleaseRelease


ReleaseRelease– Naked virusesNaked viruses

Lyse the host cellLyse the host cell

Kills the host cellKills the host cell

Virus particles released can infect other host cellsVirus particles released can infect other host cells

– Enveloped virusesEnveloped virusesMerge with the host cell membraneMerge with the host cell membrane

Form an envelope around the virusForm an envelope around the virus

The cell is not lysed and not killedThe cell is not lysed and not killed

Cell continues to produce more virusesCell continues to produce more viruses

viruses, part 2. bacteriophage multiplication lytic cycle –ends with cell lysis –death of host...

Documents

strand rna strand rna

strand rna strand

nucleus rna

cytoplasm strand rna

strand rna assembly

virus slide

nucleus assembly of

dna transcription