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Understanding the Characteristics and Classifications of Prokaryotic and Eukaryotic Organisms

This document explores the distinct characteristics of various species, focusing on the derived traits that define their uniqueness. It discusses the differences between prokaryotes and eukaryotes, particularly emphasizing prokaryotic organisms, or microbes, which lack a true nucleus. Prokaryotes are classified based on shape, nutrient acquisition, and respiration methods. The classification includes types such as Gram-positive and Gram-negative bacteria, and their metabolic preferences are illustrated through various examples. Understanding these classifications aids in the study of biology and microbiology.

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Understanding the Characteristics and Classifications of Prokaryotic and Eukaryotic Organisms

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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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