Viruses Viruses http:// http:// lbhsbio.files.wordpress.c lbhsbio.files.wordpress.c om/2008/01/bacteria-and- om/2008/01/bacteria-and- viruses-combo-2.ppt viruses-combo-2.ppt
Dec 30, 2015
VirusesViruses
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2008/01/bacteria-and-viruses-2008/01/bacteria-and-viruses-combo-2.pptcombo-2.ppt
STRUCTURESTRUCTURE NonlivingNonliving Composed of a nucleic acid and a protein coatComposed of a nucleic acid and a protein coat Cause many diseasesCause many diseases Virology – Virology – Study of VirusesStudy of Viruses Comparison of Viruses and Cells belowComparison of Viruses and Cells below
Char. Of Char. Of LifeLife
VirusVirus CellCell
GrowthGrowth NoNo YesYes
HomeostasisHomeostasis NoNo YesYes
MetabolismMetabolism NoNo YesYes
MutationMutation YesYes YesYes
Nucleic acidNucleic acid DNA or RNADNA or RNA DNADNA
ReproductionReproduction Only within host cellOnly within host cell Independently Independently by cell divisionby cell division
StructureStructure Nucleic acid core, Nucleic acid core, protein covering, some protein covering, some have envelopehave envelope
Cytoplasm, cell Cytoplasm, cell membrane, etc..membrane, etc..
Nucleic acid (DNA or RNA)
Protein Coat ( capsid)
Structure of a Virus
Characteristics of VirusesCharacteristics of Viruses
2 essential features2 essential features 1. Nucleic Acid1. Nucleic Acid
May be DNA or RNAMay be DNA or RNA Helical, closed loop, or long strandHelical, closed loop, or long strand
2. Protein Coat – called CAPSID2. Protein Coat – called CAPSID Some have ENVELOPESome have ENVELOPE
Ex. Influenza, chickepox, herpes simplex, Ex. Influenza, chickepox, herpes simplex, HIVHIV
VIRAL SHAPEVIRAL SHAPE Icosahedron – 20 triangular facesIcosahedron – 20 triangular faces
Ex.) herpes, chickenpox, polioEx.) herpes, chickenpox, polio Helix – Coiled springHelix – Coiled spring
EX.)Rabies, measles, tobacco mosaicEX.)Rabies, measles, tobacco mosaic
Grouping VirusesGrouping Viruses Grouped according to:Grouped according to:
Presence of capsid and envelope – Presence of capsid and envelope – shapeshape RNA or DNA, single or double stranded – RNA or DNA, single or double stranded – structurestructure
Viral GroupViral Group Nucleic Nucleic AcidAcid
Shape and StructureShape and Structure ExampleExample
PapovavirusPapovaviruseses
DNADNA Icosahedral, non-env.Icosahedral, non-env. Warts, cancerWarts, cancer
AdenoviruseAdenovirusess
DNADNA Icosahedral, non-env.Icosahedral, non-env. Resp. & Resp. & intestinal intestinal infectionsinfections
HerpesvirusHerpesviruseses
DNADNA Icosahedral, Icosahedral, envelopedenveloped
Herpes Herpes simplex, simplex, chicken pox, chicken pox, mono, shinglesmono, shingles
PoxvirusesPoxviruses DNADNA Complex brick, Complex brick, envelopedenveloped
Small pox, cow Small pox, cow poxpox
PicornavirusPicornaviruseses
RNARNA Icosahedral, non-env.Icosahedral, non-env. Polio, hepatitis, Polio, hepatitis, cancercancer
MyxovirusesMyxoviruses RNARNA Helical, envelopedHelical, enveloped Influenza A, B, Influenza A, B, CC
RhabdovirusRhabdoviruseses
RNARNA Helical, envelopedHelical, enveloped RabiesRabies
RetrovirusesRetroviruses RNARNA Icosahedral, Icosahedral, envelopedenveloped
AIDS, cancerAIDS, cancer
Other Grouping of VirusesOther Grouping of Viruses
Viroids- The smallest known particle Viroids- The smallest known particle that can replicate.that can replicate. Disrupt plant cell metabolismDisrupt plant cell metabolism Can destroy entire cropsCan destroy entire crops
Prions – Abnormal forms of proteins that Prions – Abnormal forms of proteins that clump together inside cells.clump together inside cells. Clumping eventually kills the cellClumping eventually kills the cell ExamplesExamples
Scrapie – in sheepScrapie – in sheep Mad Cow DiseaseMad Cow Disease
Viral ReplicationViral Replication
Can replicate only by invading host cell Can replicate only by invading host cell and using its enzyme and organelles.and using its enzyme and organelles.
Bacteriophage – viruses that infect Bacteriophage – viruses that infect bacteriabacteria Used to study virusesUsed to study viruses
Lytic Cycle of Virus Lytic Cycle of Virus ReplicationReplication
Lytic CycleLytic Cycle Viral genome is released Viral genome is released
into the host cellinto the host cell Replication follows Replication follows
immediatelyimmediately Cellular components used Cellular components used
to make new virusesto make new viruses Viral enzyme kills cell.Viral enzyme kills cell. Play animationPlay animation
Lysogenic Cycle of Virus Lysogenic Cycle of Virus ReplicationReplication
Nucleic acid of virus becomes part of the Nucleic acid of virus becomes part of the host cell’s chromosomehost cell’s chromosome
Nucleic acid remains in the cell in this form Nucleic acid remains in the cell in this form for many generationsfor many generations
HIV follows this patternHIV follows this pattern HIV infects WBC and remains as provirusesHIV infects WBC and remains as proviruses As immune system fails, opportunistic As immune system fails, opportunistic
infections occur = AIDSinfections occur = AIDS Play animationPlay animation Play animationPlay animation
Viruses and Human DiseaseViruses and Human Disease Control and Prevention of spread.Control and Prevention of spread.
Vaccination & Antiviral drugsVaccination & Antiviral drugs Ex.) chickenpox vaccine, AZT, Acyclovir, protease Ex.) chickenpox vaccine, AZT, Acyclovir, protease
inhibitors.inhibitors.
Emerging Viruses – exist in isolated habitatsEmerging Viruses – exist in isolated habitats Do not usually infect humans unless Do not usually infect humans unless
environmental conditions favor contact.environmental conditions favor contact. Several viruses are now linked to cancers Several viruses are now linked to cancers
such as leukemia, liver cancer, Burkitt’s such as leukemia, liver cancer, Burkitt’s lymphoma, cervical cancer.lymphoma, cervical cancer.
PAPOVAVIRUSESPAPOVAVIRUSES
ADENOVIRUSESADENOVIRUSES
HERPESVIRUSESHERPESVIRUSES
POXVIRUSESPOXVIRUSES
PICORNAVIRUSPICORNAVIRUSESES
After polio infections, the killer T-cell have destroyed the motor
neurons that are producing the virus. The result is a loss of
muscle control including the
diaphragm. The iron lung changes the pressure to pump air
in and out of the lungs.
MYXOVIRUSMYXOVIRUSESES
RHABDOVIRUSESRHABDOVIRUSES
RETROVIRUSESRETROVIRUSES
Research the following Research the following virusesviruses
Viral GroupViral Group
PapovavirusePapovavirusessAdenovirusesAdenoviruses
HerpesviruseHerpesvirusess
PoxvirusesPoxviruses
PicornavirusePicornavirusessMyxovirusesMyxoviruses
RhabdoviruseRhabdovirusess
RetrovirusesRetroviruses
Look at how the virus infectsLook at how the virus infects
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