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Characteristics

Characteristics. Applications. Species refers to organisms that have a distinct set of unique derived traits. Different species will have different derived traits, these could be:  physical appearance : e.g. fur thickness, snout length, body shape

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Characteristics

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  1. Characteristics Applications

  2. Speciesreferstoorganismsthathaveadistinctsetofuniquederivedtraits.Speciesreferstoorganismsthathaveadistinctsetofuniquederivedtraits. Differentspecieswillhavedifferentderivedtraits,thesecouldbe: physicalappearance:e.g.furthickness,snoutlength,bodyshape behavioural:e.g.preypreference,habitatchoice,huntingstrategy geneticcomposition:e.g.numberofchromosomes,DNAsequence Differentspeciesmaymatebutwillproducesterileoffspring e.g.Femalehorse(64c)+maledonkey(62c)mule(63c) Themulewillnothaveanydescendantsbecauseitisnotfertiledueto differencesintheirchromosomenumber!

  3. Prokaryotes Eukaryotes

  4. Prokaryote–single-celledorganismsthatlackatruenucleus Generallyreferredtoas“microbes”or“bugs” Twokingdomsofmicro-organisms:ArchaeaandEubacteria Theoverwhelmingmajorityoftheprokaryoteswedealwithona dailybasisaretheEubacteria. Archaeabacteria: Usuallyarefoundinhostileenvironments: e.g.hydrothermalvents,geysers, oilwells,highlyacidic/basic oralkalinewater. Eubacteria: everywhereelseincludinghumanbody

  5. 1.Allbacteriaaresingle-celled 2.Theyareprokaryotes–theirDNAisnotcompartmentalized 3.Cellorganellesinbacteriaarenotsurroundedbymembranes 4.TheDNAismadeofasinglechromosome 5.Allbacteriareproduceasexuallybybinaryfission

  6. •MicrobialLengthUnit: -Micrometer(µm)or‘micron’ 10-6meter(1m=1,000,000µm) -Nanometer(nm) 10-9meter(1m=1,000,000,000nm) •Bacterialcellsrangeinsizefrom10–100µm recentdiscoveriesextendthissizerangeto500–1000µm

  7. “Typical”eukaryoticcell “Typical”prokaryoticcell

  8. Cellwall–providesstructuralsupportandprotectionforcellcontentsCellwall–providesstructuralsupportandprotectionforcellcontents Cellmembrane–controlsthepassageofmaterialsintoandoutofthecell Cytoplasm–containsribosomes,responsiblefortheformationofproteins, andDNA,thegeneticinformationofthecell DNA–singlestrandedchromosomethatformsaring(Plasmid=doublestranded) Flagella/Cilia–somebacteriahavethem,stemfromthecellwallandcell membranefunctioningasapropellersthathelpbacteriamobile Bacteriaareusuallyclassifiedby: shape,reactiontobeingstained, nutrition,andrespiration (andnotbyphylogeneticrelationships).

  9. Coccus Plural:cocci sphericalcell Bacillus Plural:bacilli rod-likecell Coccobacillus Plural:coccobacilli cellsinbetweenround&rodshape Vibrio curvedcell Asapopulation:eg.Cocci Spirillum Plural:spirilla rigid,wave-likeshapedcell Spirochete corkscrewshapedcells • • • • Monococci–liveinseparatecells Diplococci–liveinpairs Streptococci–liveinlinearchains Staphlococci–liveinclusters

  10. Bacteriaarefurthergroupedbytheircellmembranecomposition. Toclassifythem,gramstainingisused.Themethodworksbycheckinghow thebacteriareacttoadyemadeofcrystalvioletandiodine. IfitisGram-positivebacteria: -canretainthedye,hencepurple -verythickcellmembrane IfitisGram-negativebacteria: -donotstainwithGramstain,henceappears red/pinkishincolor -thinnercellmembrane -hasacellwall -largeperiplasmicspace

  11. Bacteriaarealsoclassifiedbasedonhowtheyobtaintheirenergyandnutrients!Bacteriaarealsoclassifiedbasedonhowtheyobtaintheirenergyandnutrients! Autotrophs–maketheirownfood Photoautotrophs–similartophotosynthesisinplants,butnoO2isproduced; light=energy,organicandinorganiccompoundsusedfornutrients Chemoautotrophs–useinorganicsubstancestogainenergyinsteadof sunlight;inorganicchemicals=energy,organicandinorganic compoundsusedfornutrients. E.g.Cyanobacteria(foundinhydrothermalvents) Heterotrophs–consumefoodmadebyproducers Chemoheterotrophs–energyandnutrientsfromorganiccompounds (humansareexamplesofthistypeofmetabolism) Photoheterotrophs–energyfromsunlightanduseorganiccompounds fornutrients

  12. TherearespecificterminologyusedtocommunicatebacteriawithvariousTherearespecificterminologyusedtocommunicatebacteriawithvarious metabolismpreference.Sinceoxygeniscommon,thesetermsarebasedon bacterial:1)needsforoxygen;2)toleranceofoxygen;or3)aversiontooxygen Obligateaerobes–organismsthatcanonlygrowinthepresenceofO2 E.g.Bacteriathatinfecttherespiratorysystemofhumans;microorganismsthat liveinthewatercolumnoflakes,rivers,andocean Facultativeanaerobes–organismsthatcangrowinbothinthepresenceand theabsenceofO2. E.g.Bacteriainthehumanintestinescanbeexposedtoarangeofconditions fromfullyoxygenated(nearthestomach)tocompletelywithoutoxygen (furtherintotheintestines);anexampleofthistypeoforganismisE.coli. Obligateanaerobes–canonlygrowinenvironmentswherethereisnoO2 E.g.deepwoundsonskin(hencetheawfulsmell);deepinthesoiland sediments;incertainpartsofsewagetreatmentplants

  13. Howtodeterminewhichrespirationmodethe bacteriaexhibit? a)? b)? c)? Thioglycolatebrothmedium (+agar+resazurin)

  14. Howtodeterminewhichrespirationmodethe bacteriaexhibit? a)ObligatedAerobes–oxygencanonly penetrateashortdistanceintothetube b)ObligatedAnaerobes–theyaresensitiveto oxygensogrowawayfromthesurface c)FacultativeAerobes–areabletogrowin eitherthepresenceortheabsenceof oxygensogrowthroughoutthetube Thioglycolatebrothmedium (+agar+resazurin)

  15. -Bacterialcellsgrowatanexponentialratewhengiventherighttype andamountsofnutrients. -Theirmodeofreproductionisasexual,bydoublingthemselves Thiscantranslateintoadoublingofthepopulationevery20minutes!

  16. Step1.Chromosomesduplicate andcopiesgetseparated Step2.Cellelongatesandcopies ofchromosomesmove towardsthepoles Step3.Celldividesintotwo daughtercells

  17. N=Totalfinalnumberofbacteria No =Initialnumberofbacteria n=numberofgeneration (1generation=20minutes) 2indicatebinaryfission N=No2n ExampleProblems: 1.Togetreadyforlunch,Hannah washesherhandsverycarefullyafterbuildinga sandcastle.Assumingthathereffortresultedinremovingmostbacteriaoffher handsexceptfor36bacteria.Bythetimeshepicksupthesandwichtoeat15 minuteslater,howmanybacteriaarethereonherhandsatthattime? Given: No=36 N=? N= = = = No2n 36•(20.75) 36•1.68 61 15 n=15min20=0.75 Therefore,Hannah has61bacteria..

  18. BinaryFission: asexualprocessofreproduction andthereforelacksexchangeof geneticmaterial. Transformation: BacteriapicksuprandomDNA fragmentintheenvironment (e.g.fromotherbacteriathat died)&incorporatedintoits genome. Conjugation: thetransferofgenesfromone celltoanotherandtherefore increasesgeneticdiversityofa population.

  19. Step1.F+cell(donor)makes contactwithF-cell(recipient) viatheirtubulepilus Step2.Conjugationtubeformatsite ofcontactbridgingthe2cells Step3.Single-strandedDNAofthe plasmidgetstransferredtothe recipientcell Step4.Conjugationtubedisconnects. Single-strandedDNAfromeach cellduplicatesmakingbothF+cells

  20. BacteriaandDiseases: Notallbacteriacausedisease,butsomedoaspartoftheirmetabolism. Thesefew“bad”bugsgivebacteriathegroupnameof“germs” - - Pathogen–diseasecausingagent -Twogeneralwaysapathogencanoperate: Breakdowntissuesforfood(e.g.Tuberculosis) Releasetoxinsthatharmthehost(e.g.Foodpoisoning) -Manybacteriacanbekilledorkeptincheckwithantibioticsorvaccines Butproblemsarisewhenbacteriabecomeresistanttoourdrugs. Howwouldthisaffectyou? -

  21. Decomposers: -Bacteriaplayacriticalroleinnaturebyrecyclingdeadorganisms Nutrientsindeadorganismscanbereused,insteadofaccumulating Thisrequirestherightmixofthefollowingvariablesformaximum decompositiontooccur: i)Temperature ii)Gasavailabilityforterminalelectronaccepting(O2isthebest) iii)Water -Widelyusedbyhumanstoprocessdeadmaterials asdetrivoretogetridofthemortorecyclethem. e.g.bacteriaeatingUranium

  22. FixingNitrogen: -Certainbacteriacanconvertuselessnitrogentousefulnitrogen(fertilizer) thatcanbeusedbyotherorganisms N2gas(abundancebutuseless) NH3(ammonia)&othercompounds -Thisabilitytotransformnitrogeniscallednitrogenfixation -Nitrogenfixingbacteriaareoftenfoundinrootnodulesoflegumes(plants) theserootnodulesarefunctionallyequaltofertilizerfactory plantsharbouringthesefixing bacteriagrowrelatively fasterandhealthier.

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