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Ch.21BacteriaandViruses 21.1Viruses

I.Whatisavirus?

1.  Non-livingorganismthatinfectlivingcells2.  Par?clesofnucleicacid(DNAorRNA),

proteinandsome?meslipids3.  Outercovering=capsid

a)  Hasproteinsthatallowittogetinsidecellsb)  AlsohasproteinsthatcantrickcellintoNOT

recognizingitisavirus

I.Whatisavirus?

4.  Varyinshape,butaresmallerthanbacteria5.  Species-specific–canonlyinfectcertain

organisms

Differenttypesofviruses II.ViralInfec?onp.685

1.  Ly?cinfec?on–shortinfec?on,lastsafewdaystoaweek

•  Examples:commoncold,flu,AIDS,Ebola

a)  Virusentersthecellb)  Makescopiesofitselfc)  Causesthecelltoburst,releasesmanyviruses

intothebody

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II.ViralInfec?on

2.  LysogenicInfec?on–long-terminfec?on•  Examples:HIV,Herpes

a)  VirusinjectsDNAintohostcellb)  HostcellcopiesviralDNAalongwithitsownc)  Every?methehostcelldivides,itmakesanew

cellcontainingtheviralDNAd)  Somethingtriggersthevirustocomeoutof

dormancy,thenentersthely?ccycle

ViralInfec?on(copydiagram)Viruses Living Cells

Structure: DNA or RNA and Protein Cell membranes, nucleus, organelles, cytoplasm

Reproduction: Only inside host Asexual or sexual independent

Genetic Code: DNA or RNA DNA

Growth: No Yes - increase in size and cell number

Obtain & Use Energy: No Yes

Respond to Environment: No Yes

Change over Time: Yes Yes

III.Pathogens

•  Disease-causingagents

IV.ViralDiseasesinHumans

•  Virusesproducediseasebydisrup?nghomeostasis

•  Examples:commoncold,flu,AIDS,chickenpox,hepa??sB,WestNile

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A.Preven?ngViruses

1.  Viralvaccines2.  OTCmedica?onstohelpwithsymptoms–

doesNOTcureviruses

B.AnimalViruses

•  Some?mesen?regroups/herdsofanimalswillbekilled

C.PlantViruses

•  Tobaccomosaicvirus–infectsagriculturalcrops

•  Hardertoinfectplantcellsthananimalcells•  Enterthroughtearsinleaves,roots,andstems

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20.2Bacteria

Review:ProkaryoteandEukaryote

•  Prokaryote–hasnonucleus,bacteria•  Eukaryote–hasnucleus,plants,animals,fungi

2GroupsofProkaryotes

Archaebacteria

•  CellwallDOESNOThavepep?doglycan

•  Differentmembranelipids•  DNAmorecloselyresemble

eukaryotes•  Mayliveinextreme

environments

Eubacteria

•  Cellwallhaspep?doglycan•  Verydiverse

Ar?cleonPep?doglycan…

•  hdp://blogs.scien?ficamerican.com/disease-prone/2011/09/14/pep?doglycan-the-bacterial-wonder-wall/

Iden?fyprokaryotesby:

1.  Shape2.  Cellwallcomposi?on3.  Thewaytheymove(mobility)4.  Thewaytheyobtainenergy

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1.Shapes

•  Bacilli(bacillus)-rodshaped•  Cocci(coccus)-sphericalshaped•  Spirilla(spirillum)-spiralshaped

Bacilli–rodshaped

Cocci–spherical Spirilla–corkscrew-shaped

2.Cellwallcomposi?on-GramStaining

•  Gram-posi?ve–containpep?doglycan,stainspurple– Hasonlyonecellwall

•  Gram-nega?ve–nopep?doglycan,stainsredorpink– Hasanouterlayeroflipidandcarbohydrates=moredifficulttokill

3.Mobility

•  Flagella•  Lash,snakeorspiralforward•  gliding

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Flagella Gliding

4.ObtainingEnergy

Heterotrophs•  Takeinorganicmolecules

forenergyandcarbon•  Chemoheterotrophs•  photoheterotrophs

Autotrophs•  Convertinorganicmolecules

tomakefood•  Photoautotrophs•  Chemoautotrophs

4.bReleasingEnergy

•  Energyreleasedbycellularrespira?onand/orfermenta?on

1.  obligateaerobes–musthaveoxygen2.  Obligateanaerobes–mustNOThaveoxygen3.  Faculta?veanaerobes–may/maynothave

oxygen

Reproduc?on

1.  BinaryFission-–  asexualform–  1celldividesintotwo

2.  Conjuga?on–  sexualform–  2cellsexchangeDNAthroughahollowtube

3.  Sporeforma?on–  Allowsbacteriatosurviveduringunfavorable

condi?ons

Binaryfission:

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Conjuga?on Spores

WhyisBacteriaimportant?

•  Captureenergythroughphotosynthesis•  Decomposers

– breakdownorganicmader

•  Nitrogenfixers– onrootsofplantstohelpthemgetusablenitrogen

•  Humanuses– Foodandbeverages,wastetreatment

ListoffoodsanddrinksmadewithBacteria…

•  hdp://en.wikipedia.org/wiki/List_of_microorganisms_used_in_food_and_beverage_prepara?on

•  Worksheet•  hdp://teachersites.schoolworld.com/webpages/bertoloi/files/chapter%2019%20worksheet-%20bacteria%20and%20viruses.pdf

I.BacterialDiseaseinHumans

•  Examples:Lymedisease,tetanus,tuberculosis,bacterialmeningi?s,strepthroat

A.2WaysBacteriaCauseDisease

•  1.Usecell/?ssueforfood•  2.Releasetoxinsintothebody

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B.Preven?ngBacterialDisease

•  1.Bacterialvaccine•  2.An?bio?cs–blockgrowthandreproduc?onofbacteria***DonotworkonViruses***

II.ControllingBacteria

1.  Steriliza?onbyheat–killallbacteriabyexposuretohighheat

2.  Disinfectants–usingchemicalstokillbacteria

3.  Foodprepera?onandstorage•  Storeinrefrigerator•  Freeze•  Boiling,frying,steaming•  Pickling•  canning