1.
Microbiology: AMicrobiology: A
Systems Approach, 2Systems Approach, 2ndnd
ed.ed.
Chapter 5: Eukaryotic Cells andChapter 5: Eukaryotic Cells and
MicroorganismsMicroorganisms

2.
5.1 The History of Eukaryotes5.1 The History of Eukaryotes
 First eukaryotic cells on earth approximately 2First eukaryotic cells on earth approximately 2
billion years agobillion years ago
 Evidence points to these eukaryotic cells evolvingEvidence points to these eukaryotic cells evolving
from prokaryotic organisms through intracellularfrom prokaryotic organisms through intracellular
symbiosissymbiosis

EukaryoticEukaryotic organellesorganelles originated from prokaryoticoriginated from prokaryotic
cells trapped inside of themcells trapped inside of them

First primitive eukaryotes- probably single-celled andFirst primitive eukaryotes- probably single-celled and
independentindependent

Eventually formed coloniesEventually formed colonies

Cells within colonies became specializedCells within colonies became specialized

Evolved in to multicellular organismsEvolved in to multicellular organisms
 Eukaryotes have many levels of cellularEukaryotes have many levels of cellular
complexitycomplexity

3.
5.2 Form and Function of the5.2 Form and Function of the
Eukaryotic Cell: External StructuresEukaryotic Cell: External Structures
Figure 5.2

4.
Locomotor Appendages: Cilia andLocomotor Appendages: Cilia and
FlagellaFlagella
 Eukaryotic flagella are much different fromEukaryotic flagella are much different from
those of prokaryotesthose of prokaryotes

10X thicker10X thicker

Structurally more complexStructurally more complex

Covered by an extension of the cellCovered by an extension of the cell
membranemembrane
 A single flagellum contains regularlyA single flagellum contains regularly
spaced microtubules along its lengthspaced microtubules along its length

9 pairs surrounding a single pair9 pairs surrounding a single pair

The 9 + 2 arrangementThe 9 + 2 arrangement

5.
Figure 5.3

6.
 Cilia- similar to flagella but someCilia- similar to flagella but some
differencesdifferences

ShorterShorter

More numerousMore numerous

Can also function as feeding and filteringCan also function as feeding and filtering
structuresstructures

7.
The GlycocalyxThe Glycocalyx
 Most eukaryotic cells have this outermostMost eukaryotic cells have this outermost
boundary that comes into direct contact with theboundary that comes into direct contact with the
environmentenvironment
 Usually composed of polysaccharidesUsually composed of polysaccharides
 Appears as a network of fibers, a slime layer, or aAppears as a network of fibers, a slime layer, or a
capsulecapsule
 FunctionsFunctions

ProtectionProtection

AdhesionAdhesion

Reception of signalsReception of signals
 The layer beneath the glycocalyx varies amongThe layer beneath the glycocalyx varies among
eukaryoteseukaryotes

Fungi and most algae have a thick, rigid cell wallFungi and most algae have a thick, rigid cell wall

Protozoa and animal cells do not have this cell wallProtozoa and animal cells do not have this cell wall

8.
Form and Function of the EukaryoticForm and Function of the Eukaryotic
Cell: Boundary StructuresCell: Boundary Structures
 Cell WallCell Wall

RigidRigid

Provide support and shapeProvide support and shape

Different chemically from prokaryotic cell wallsDifferent chemically from prokaryotic cell walls

FungiFungi
• Thick, inner layer of chitin or celluloseThick, inner layer of chitin or cellulose
• Thin outer layer of mixed glycansThin outer layer of mixed glycans

AlgaeAlgae
• Varied in chemical compositionVaried in chemical composition
• May contain cellulose, pectin, mannans, andMay contain cellulose, pectin, mannans, and
mineralsminerals

9.
Figure 5.5

10.
 Cytoplasmic MembraneCytoplasmic Membrane
 Bilayer of phospholipids with proteinBilayer of phospholipids with protein
molecules embeddedmolecules embedded
 Also contain sterolsAlso contain sterols
• Gives stabilityGives stability
• Especially important in cells without a cell wallEspecially important in cells without a cell wall
 Selectively permeableSelectively permeable

11.
5.3 Form and Function of the5.3 Form and Function of the
Eukaryotic Cell: Internal StructuresEukaryotic Cell: Internal Structures
 The Nucleus: The Control CenterThe Nucleus: The Control Center

Separated from the cytoplasm by a nuclearSeparated from the cytoplasm by a nuclear
envelopeenvelope
• Two parallel membranes separated by a narrow spaceTwo parallel membranes separated by a narrow space
• Perforated with nuclear poresPerforated with nuclear pores

Filled with nucleoplasmFilled with nucleoplasm

Contains theContains the nucleolusnucleolus
• rRNA synthesisrRNA synthesis
• Colelction area for ribosomal subunitsColelction area for ribosomal subunits

ChromatinChromatin
• Comprises theComprises the chromosomeschromosomes

Long, linear DNA moleculesLong, linear DNA molecules

Bound toBound to histonehistone proteinsproteins

Visible duringVisible during mitosismitosis

12.
Figure 5.6

13.
Figure 5.7

14.
Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER): A: A
Passageway in the CellPassageway in the Cell
 Microscopic series of tunnelsMicroscopic series of tunnels
 Used in transport and storageUsed in transport and storage
 Two kindsTwo kinds

Rough endoplasmic reticulum (RER)Rough endoplasmic reticulum (RER)
• Originates from the outer membrane of the nuclearOriginates from the outer membrane of the nuclear
envelopeenvelope
• Extends through the cytoplasmExtends through the cytoplasm
• Spaces in the RER- cisternae- transport materials fromSpaces in the RER- cisternae- transport materials from
the nucleus to the cytoplasmthe nucleus to the cytoplasm
• ““Rough” because of ribosomes attached to its surfaceRough” because of ribosomes attached to its surface
• Proteins synthesized on the ribosomes shunted into theProteins synthesized on the ribosomes shunted into the
cavity of the RER and held for later packaging andcavity of the RER and held for later packaging and
transporttransport

15.
Figure 5.8

16.
 Smooth endoplasmic reticulum (SER)Smooth endoplasmic reticulum (SER)
 Closed tubular networkClosed tubular network
 No ribosomesNo ribosomes
 FunctionsFunctions
• Nutrient processingNutrient processing
• Synthesis and storage of nonproteinSynthesis and storage of nonprotein
macromoleculesmacromolecules

17.
Golgi ApparatusGolgi Apparatus: A Packaging: A Packaging
MachineMachine
 Where proteins are modified and sent to their finalWhere proteins are modified and sent to their final
destinationsdestinations
 A stack of cisternaeA stack of cisternae
 Do not form a continuous networkDo not form a continuous network
 Closely associated with ER both in location andClosely associated with ER both in location and
functionfunction

The ER buds off transitional vesicles (packets ofThe ER buds off transitional vesicles (packets of
protein) where it meets the Golgi apparatusprotein) where it meets the Golgi apparatus

The Golgi apparatus picks up the transitional vesiclesThe Golgi apparatus picks up the transitional vesicles

The proteins are often modified by addition ofThe proteins are often modified by addition of
polysaccharides and lipidspolysaccharides and lipids

Then the apparatus pinches off condensing vesiclesThen the apparatus pinches off condensing vesicles
• Sent toSent to lysosomeslysosomes
• Or transported outside the cellOr transported outside the cell

18.
Figure 5.9

19.
Figure 5.10

20.
Figure 5.11

21.
MitochondriaMitochondria: Energy: Energy
GeneratorsGenerators
 Cellular activities require a constant supply ofCellular activities require a constant supply of
energyenergy
 The bulk of this energy generated by mitochondriaThe bulk of this energy generated by mitochondria
 Smooth, continuous outer membraneSmooth, continuous outer membrane
 Inner folded membrane (folds areInner folded membrane (folds are cristaecristae))

Cristae hold enzymes and electron carriers of aerobicCristae hold enzymes and electron carriers of aerobic
respirationrespiration

Spaces around cristae filled with aSpaces around cristae filled with a matrixmatrix
• RibosomesRibosomes
• DNADNA
• Enzymes and other compounds involved I the metabolicEnzymes and other compounds involved I the metabolic
cyclecycle
 Divide independently of the cellDivide independently of the cell
 Contain circular strands of DNAContain circular strands of DNA
 Contain prokaryotic-sized 70S ribosomesContain prokaryotic-sized 70S ribosomes

22.
Figure 5.12

23.
ChloroplastsChloroplasts: Photosynthesis: Photosynthesis
MachinesMachines
 Organelles found in algae and plant cellsOrganelles found in algae and plant cells
 Convert energy of sunlight into chemicalConvert energy of sunlight into chemical
energy through photosynthesisenergy through photosynthesis
 Two membranesTwo membranes

Smooth outer membraneSmooth outer membrane

Inner membrane folded in toInner membrane folded in to thylakoidsthylakoids

Thylakoids stacked upon one another intoThylakoids stacked upon one another into granagrana

Contain chlorophyll and sometimes otherContain chlorophyll and sometimes other
pigmentspigments
 StromaStroma surrounds the thylakoidssurrounds the thylakoids

24.
Figure 5.13

25.
Ribosomes: ProteinRibosomes: Protein
SynthesizersSynthesizers
 Some scattered in the cytoplasm andSome scattered in the cytoplasm and
cytoskeletoncytoskeleton
 Others associated with REROthers associated with RER
 Often found in chains of polyribosomesOften found in chains of polyribosomes
(polysomes)(polysomes)
 Composed of large and small subunits ofComposed of large and small subunits of
ribonucleoproteinribonucleoprotein
 Larger 80S variety, composed of 60S andLarger 80S variety, composed of 60S and
40S subunits40S subunits

26.
The Cytoskeleton: A Support NetworkThe Cytoskeleton: A Support Network
 Flexible framework of molecules criss-Flexible framework of molecules criss-
crossing the cytoplasmcrossing the cytoplasm
 Several functionsSeveral functions

Anchoring organellesAnchoring organelles

Moving RNA and vesiclesMoving RNA and vesicles

Permitting shape changes and movement inPermitting shape changes and movement in
some cellssome cells
 Two types: Microfilaments andTwo types: Microfilaments and
microtubulesmicrotubules

27.
MicrofilamentsMicrofilaments
 Thin protein strandsThin protein strands
 Attach to the cell membraneAttach to the cell membrane
 Some responsible for movements of theSome responsible for movements of the
cytoplasmcytoplasm
 Some active in amoeboid motionSome active in amoeboid motion

28.
MicrotubulesMicrotubules
 Long, hollow tubesLong, hollow tubes
 Maintain the shape of eukaryotic cellsMaintain the shape of eukaryotic cells
without wallswithout walls
 Transport substancesTransport substances
 Responsible for the movement of cilia andResponsible for the movement of cilia and
flagellaflagella

29.
Figure 5.14

30.
5.4 The Kingdom of the5.4 The Kingdom of the FungiFungi
 MyceteaeMyceteae
 Great variety and complexityGreat variety and complexity
 Approximately 100,000 speciesApproximately 100,000 species
 Can be divided into two groups:Can be divided into two groups:

Macroscopic fungiMacroscopic fungi

Microscopic fungi:Microscopic fungi:
• YeastsYeasts

Round or oval shapeRound or oval shape

Unique mode of asexual reproductionUnique mode of asexual reproduction

Some form pseudohyphae (false filaments)Some form pseudohyphae (false filaments)
• MoldsMolds

Long, threadlike cellsLong, threadlike cells

Filamentous arrangement (hyphae)Filamentous arrangement (hyphae)
• Some are dimorphic (yeast-like and filamentous forms exist)Some are dimorphic (yeast-like and filamentous forms exist)
 Majority are unicellular or colonialMajority are unicellular or colonial

31.
Figure 5.15

32.
Figure 5.16

33.
Fungal NutritionFungal Nutrition
 HeterotrophicHeterotrophic
 Acquire nutrients fromAcquire nutrients from substratessubstrates
 Most fungi areMost fungi are saprobessaprobes
 Can also beCan also be parasitesparasites
 General method of obtaining nutritionGeneral method of obtaining nutrition

Penetrates the substratePenetrates the substrate

Secretes enzymesSecretes enzymes

Breaks down the enzymes into small moleculesBreaks down the enzymes into small molecules

Absorbs the moleculesAbsorbs the molecules
 Can absorb a wide variety of substratesCan absorb a wide variety of substrates
 Large medical and agricultural importanceLarge medical and agricultural importance

34.
Figure 5.17

35.
Organization of MicroscopicOrganization of Microscopic
FungiFungi
 Most grow in loose associations or coloniesMost grow in loose associations or colonies
 Yeasts- soft, uniform texture and appearanceYeasts- soft, uniform texture and appearance
 Filamentous fungal colonies- cottony, hairy, or velvetyFilamentous fungal colonies- cottony, hairy, or velvety
texturestextures
 MyceliumMycelium- the woven, intertwining mass of hyphae that- the woven, intertwining mass of hyphae that
makes up the body or colony of a moldmakes up the body or colony of a mold
 Unique organizational features of hyphaeUnique organizational features of hyphae

SeptaSepta- divide the hyphae into segments (most fungi have- divide the hyphae into segments (most fungi have
septate hyphae)septate hyphae)

Nonseptate hyphae- one long, continuous, multinucleateNonseptate hyphae- one long, continuous, multinucleate
cellcell
 Functions of hyphaeFunctions of hyphae

Vegetative hyphae (mycelia)- visible mass of growth on theVegetative hyphae (mycelia)- visible mass of growth on the
substrate surface; penetrates the substrate to digest andsubstrate surface; penetrates the substrate to digest and
absorb nutrientsabsorb nutrients

Reproductive (fertile) hyphae- from vegetative hyphae;Reproductive (fertile) hyphae- from vegetative hyphae;
responsible for the production ofresponsible for the production of sporesspores

36.
Figure 5.18

37.
Reproductive Strategies and SporeReproductive Strategies and Spore
FormationFormation
 Most can propagate by growth of hyphae orMost can propagate by growth of hyphae or
fragmentationfragmentation
 Primary reproductive mode- the production ofPrimary reproductive mode- the production of
sporesspores
 Function of sporesFunction of spores

MultiplicationMultiplication

SurvivalSurvival

Producing genetic variationProducing genetic variation

DisseminationDissemination
 Large diversity in spores among the fungiLarge diversity in spores among the fungi
•
General grouping of spores- asexual and sexualGeneral grouping of spores- asexual and sexual

38.
Asexual SporesAsexual Spores
 SporangiosporesSporangiospores

Formed by successive cleavages within theFormed by successive cleavages within the
sporangiumsporangium

Sporangium attached to the sporangiophoreSporangium attached to the sporangiophore

Released when the sporangium rupturesReleased when the sporangium ruptures
 ConidiosporesConidiospores

AkaAka conidiaconidia

Free sporesFree spores

Develop either by pinching off the tip of fertileDevelop either by pinching off the tip of fertile
hypha or by segmentation of a vegetative hyphahypha or by segmentation of a vegetative hypha

39.
Figure 5.19

40.
Sexual SporesSexual Spores
 Increases genetic variationIncreases genetic variation
 Majority of fungi produce sexual spores atMajority of fungi produce sexual spores at
some pointsome point

41.
Fungal Identification and CultivationFungal Identification and Cultivation
 Medical specimensMedical specimens

Isolated on special types of mediaIsolated on special types of media

Observed macroscopically and microscopicallyObserved macroscopically and microscopically
 Usually use sexual spore-forming structuresUsually use sexual spore-forming structures
and sporesand spores
 Other characteristics that contribute toOther characteristics that contribute to
identificationidentification

Hyphal typeHyphal type

Colony texture and pigmentationColony texture and pigmentation

Physiological characteristicsPhysiological characteristics

Genetic makeupGenetic makeup

42.
The Roles of Fungi in Nature andThe Roles of Fungi in Nature and
IndustryIndustry
 Nearly all fungi are free-living and don’t needNearly all fungi are free-living and don’t need
a hosta host
 Human infection by pathogenic fungi usuallyHuman infection by pathogenic fungi usually
occurs through accidental contactoccurs through accidental contact
 Humans are generally resistant to fungalHumans are generally resistant to fungal
infection, except for two main typesinfection, except for two main types

Primary pathogensPrimary pathogens

Opportunistic pathogensOpportunistic pathogens
 Mycoses vary in the way the agent enters theMycoses vary in the way the agent enters the
body and the degree of tissue involvementbody and the degree of tissue involvement

43.
 Not only involved in infectionsNot only involved in infections
 AllergiesAllergies
 PoisoningPoisoning
 Agricultural damageAgricultural damage
 Benefits of fungiBenefits of fungi
 Decomposing organic matter and returningDecomposing organic matter and returning
essential minerals to the soilessential minerals to the soil
 Mycorrhizae increase the ability of plant roots toMycorrhizae increase the ability of plant roots to
absorb water and nutrientsabsorb water and nutrients
 Production ofProduction of
• AntibioticsAntibiotics
• AlcoholAlcohol
• Organic acidsOrganic acids
• VitaminsVitamins
 Food flavoringsFood flavorings

44.
5.5 The Protists5.5 The Protists
 Traditionally contains the algae andTraditionally contains the algae and
protozoaprotozoa
 Two major taxonomic categoriesTwo major taxonomic categories

Subkingdom AlgaeSubkingdom Algae

Subkingdom ProtozoaSubkingdom Protozoa
 Any unicellular or colonial organism thatAny unicellular or colonial organism that
lacks true tissueslacks true tissues

45.
TheThe AlgaeAlgae: Photosynthetic: Photosynthetic
protistsprotists
 Vary in length from a few micrometers to 100Vary in length from a few micrometers to 100
metersmeters
 Unicellular, colonial, and filamentous formsUnicellular, colonial, and filamentous forms
 Larger forms can possess tissues and simpleLarger forms can possess tissues and simple
organsorgans
 Exhibit all eukaryotic organellesExhibit all eukaryotic organelles
 Chloroplasts contain chlorophyll as well as otherChloroplasts contain chlorophyll as well as other
pigmentspigments
 One of the main components ofOne of the main components of planktonplankton
 Rarely infectiousRarely infectious
 Primary medical threat: shellfish exposed to redPrimary medical threat: shellfish exposed to red
tidetide

46.
Figure 5.21

47.
Biology of the ProtozoaBiology of the Protozoa
 About 65,000 speciesAbout 65,000 species
 Most are harmless, free-living inhabitantsMost are harmless, free-living inhabitants
of water and soilof water and soil
 Few are parasitesFew are parasites

48.
Protozoan Form and FunctionProtozoan Form and Function
 Most are single cellsMost are single cells
 Contain major eukaryotic organelles exceptContain major eukaryotic organelles except
chloroplastschloroplasts
 Cytoplasm usually dividedCytoplasm usually divided

EctoplasmEctoplasm: clear outer layer involved in locomotion,: clear outer layer involved in locomotion,
feeding, and protectionfeeding, and protection

Endoplasm: granular inner region housing the nucleus,Endoplasm: granular inner region housing the nucleus,
mitochondria, and food and contractile vacuolesmitochondria, and food and contractile vacuoles
 Some ciliates and flagellates have organelles workingSome ciliates and flagellates have organelles working
like a primitive nervous systemlike a primitive nervous system
 No cell wall- so some flexibilityNo cell wall- so some flexibility
 Cell shape can remain constant or can changeCell shape can remain constant or can change
constantly (amoebas)constantly (amoebas)
 Size between 3 to 300 µmSize between 3 to 300 µm

49.
Nutritional and Habitat RangeNutritional and Habitat Range
 HeterotrophicHeterotrophic
 Usually require their food in a complex organic formUsually require their food in a complex organic form
 Free-living species scavenge or grazeFree-living species scavenge or graze
 Some have special feeding structures such as oralSome have special feeding structures such as oral
grooves; some absorb food directly through the cellgrooves; some absorb food directly through the cell
membranemembrane
 Parasitic species live on the fluids of their host; or canParasitic species live on the fluids of their host; or can
actively feed on tissuesactively feed on tissues
 Predominant habitatsPredominant habitats

Fresh and marine waterFresh and marine water

SoilSoil

PlantsPlants

AnimalsAnimals
 Many can convert to a resistant, dormant stage calledMany can convert to a resistant, dormant stage called
a cysta cyst

50.
Styles of LocomotionStyles of Locomotion
 All but the Apicomplexa are motile by means ofAll but the Apicomplexa are motile by means of
pseudopodspseudopods,, flagellaflagella, or, or ciliacilia
 Some unusual species move by gliding or twistingSome unusual species move by gliding or twisting
 PseudopodsPseudopods

Amoeboid motionAmoeboid motion

Can serve as feeding structuresCan serve as feeding structures
 FlagellaFlagella

From one to severalFrom one to several

Some attached along the length of the cell by theSome attached along the length of the cell by the
undulating membraneundulating membrane
 CiliaCilia

Mostly distributed over the entire surface of the cellMostly distributed over the entire surface of the cell

Form characteristic patternsForm characteristic patterns

51.
Life Cycles and ReproductionLife Cycles and Reproduction
Figure 5.22

52.
 Vary from simple to complexVary from simple to complex
 Some exist only inSome exist only in trophozoitetrophozoite stagestage
 Others alternate between trophozoite andOthers alternate between trophozoite and
cystcyst
 Life cycle of a parasitic protozoanLife cycle of a parasitic protozoan
determines the mode of transmission todetermines the mode of transmission to
hostshosts
 All reproduce by asexual methodsAll reproduce by asexual methods
 Usually mitotic cell divisionUsually mitotic cell division
 Some by multiple fissionSome by multiple fission
 Sexual reproduction occurs during the lifeSexual reproduction occurs during the life
cycle of most protozoacycle of most protozoa
 Ciliates participate inCiliates participate in conjugationconjugation

53.
Classification of Selected MedicallyClassification of Selected Medically
Important ProtozoaImportant Protozoa
•
Four groupsFour groups
•
Based on:Based on:
• Method of motilityMethod of motility
• Mode of reproductionMode of reproduction
• Stages in the lifecycleStages in the lifecycle

54.
MastigophoraMastigophora (Flagellated)(Flagellated)
 Motility primarily by flagellaMotility primarily by flagella
 Single nucleusSingle nucleus
 Sexual reproduction by syngamySexual reproduction by syngamy
 Division by longitudinal fissionDivision by longitudinal fission
 Parasitic forms tend to lack mitochondria andParasitic forms tend to lack mitochondria and
Golgi apparatusGolgi apparatus
 Most form cysts and are free-livingMost form cysts and are free-living
 Most are solitaryMost are solitary
 ExamplesExamples

TrypanosomaTrypanosoma

LeishmaniaLeishmania

GiardiaGiardia

TrichomonasTrichomonas

55.
Figure 5.23

56.
SarcodinaSarcodina (Amoebas)(Amoebas)
 PseudopodsPseudopods
 Some have flagellated reproductive statesSome have flagellated reproductive states
 Asexual reproduction by fissionAsexual reproduction by fission
 Two groups have an external shellTwo groups have an external shell
 Mostly uninucleateMostly uninucleate
 Usually encystUsually encyst
 Most free-livingMost free-living
 ExamplesExamples

EntamoebaEntamoeba

ForaminiferaForaminifera

RadiolariansRadiolarians

57.
Figure 5.24

58.
CiliophoraCiliophora (Ciliated)(Ciliated)
 Trophozoites mobile by ciliaTrophozoites mobile by cilia
 Some have cilia in tufts for feeding andSome have cilia in tufts for feeding and
attachmentattachment
 Most develop cystsMost develop cysts
 Both macronuclei and micronucleiBoth macronuclei and micronuclei
 Division by transverse fissionDivision by transverse fission
 Most have definite mouth and feedingMost have definite mouth and feeding
organelleorganelle
 Show relatively advanced behaviorShow relatively advanced behavior
 Majority are free-living and harmlessMajority are free-living and harmless

59.
Figure 5.25

60.
ApicomplexaApicomplexa (Sporozoa)(Sporozoa)
 Most not motile except male gametesMost not motile except male gametes
 Complex life cyclesComplex life cycles
 ProduceProduce sporozoitessporozoites following sexualfollowing sexual
reproductionreproduction
 Important in transmission of infectionsImportant in transmission of infections
 Most form oocystsMost form oocysts
 Entire group is parasiticEntire group is parasitic
 ExamplesExamples

PlasmodiumPlasmodium

Toxoplasma gondiiToxoplasma gondii

61.
Figure 5.26

62.
Protozoan Identification andProtozoan Identification and
CultivationCultivation
 Shape and size of cellShape and size of cell
 Type, number, and distribution ofType, number, and distribution of
locomotor structureslocomotor structures
 Presence of special organelles or cystsPresence of special organelles or cysts
 Number of nucleiNumber of nuclei
 Can be cultivated on artificial media or inCan be cultivated on artificial media or in
laboratory animalslaboratory animals

63.
Important Protozoan PathogensImportant Protozoan Pathogens

64.
Pathogenic Flagellates:Pathogenic Flagellates:
TrypanosomesTrypanosomes
 GenusGenus TrypanosomaTrypanosoma
 T. bruceiT. brucei causes sleeping sicknesscauses sleeping sickness
 T. cruziT. cruzi causes Chagas diseasecauses Chagas disease

65.
Figure 5.27

66.
Infective Amoebas:Infective Amoebas: EntamoebaEntamoeba
 Amoebiasis caused byAmoebiasis caused by EntamoebaEntamoeba
histolyticahistolytica
 Fourth most common protozoan infectionFourth most common protozoan infection
in the worldin the world
 Aka amoebic dysenteryAka amoebic dysentery

67.
Figure 5.28

68.
5.6 The Parasitic Helminths5.6 The Parasitic Helminths
 Tapeworms, flukes, and roundwormsTapeworms, flukes, and roundworms
 Adults large enough to be seen with theAdults large enough to be seen with the
naked eyenaked eye
 From 1 mm to 25 m in lengthFrom 1 mm to 25 m in length
 Microscope is necessary to identify eggsMicroscope is necessary to identify eggs
and larvaeand larvae
 Two major groups: Flatworms andTwo major groups: Flatworms and
RoundwormsRoundworms

69.
FlatwormsFlatworms
 Phylum PlatyhelminthesPhylum Platyhelminthes
 ThinThin
 Often segmentedOften segmented
 SubdivisionsSubdivisions

CestodesCestodes (tapeworms)(tapeworms)

TrematodesTrematodes (flukes)(flukes)

70.
Figure 5.29

71.
RoundwormsRoundworms
 Phylum AschelminthesPhylum Aschelminthes
 AkaAka nematodesnematodes
 ElongateElongate
 CylindricalCylindrical
 UnsegmentedUnsegmented

72.
Figure 5.30

73.
General Worm MorphologyGeneral Worm Morphology
 Most developed organs are those of theMost developed organs are those of the
reproductive tractreproductive tract
 Some degree of reduction in digestive,Some degree of reduction in digestive,
excretory, nervous, and muscular systemsexcretory, nervous, and muscular systems
 Most have thick cuticles for protection andMost have thick cuticles for protection and
mouth glands for breaking down the host’smouth glands for breaking down the host’s
tissuetissue

74.
Life Cycles and ReproductionLife Cycles and Reproduction
 Fertilized egg (embryo), larval, and adultFertilized egg (embryo), larval, and adult
stagesstages
 In most, adults derive nutrients andIn most, adults derive nutrients and
reproduce sexually in a host’s bodyreproduce sexually in a host’s body

Nematodes- separate sexesNematodes- separate sexes

Trematodes- separate sexes orTrematodes- separate sexes or hermaphroditichermaphroditic
 Must complete the life cycle by transmittingMust complete the life cycle by transmitting
an infective form to the body of another hostan infective form to the body of another host

Larval development- intermediate (secondary)Larval development- intermediate (secondary)
hosthost

Adulthood and mating-Adulthood and mating- definitive (final) hostdefinitive (final) host

75.
A Helminth Cycle: TheA Helminth Cycle: The
PinwormPinworm Person swallows microscopic eggsPerson swallows microscopic eggs

Picked up from another infected person by directPicked up from another infected person by direct
contactcontact

Or by touching articles an infected person hasOr by touching articles an infected person has
touchedtouched
 Eggs hatch in the intestineEggs hatch in the intestine
 Release larvae that mature in to adult wormsRelease larvae that mature in to adult worms
(about 1 month)(about 1 month)
 Male and female worms mateMale and female worms mate
 Female migrates out of the anus to deposit eggsFemale migrates out of the anus to deposit eggs

Causes intense itchinessCauses intense itchiness

Relieved by scratchingRelieved by scratching

Scratching contaminates the fingers which transferScratching contaminates the fingers which transfer
the eggsthe eggs
 Eggs spread to others or the original host reinfectsEggs spread to others or the original host reinfects
him or herselfhim or herself

76.
Helminth Classification andHelminth Classification and
IdentificationIdentification
 ShapeShape
 SizeSize
 Degree of development of various organsDegree of development of various organs
 Presence of hooks, suckers, or otherPresence of hooks, suckers, or other
special structuresspecial structures
 Mode of reproductionMode of reproduction
 Kinds of hostsKinds of hosts
 Appearance of eggs and larvaeAppearance of eggs and larvae

77.
Distribution and Importance ofDistribution and Importance of
Parasitic WormsParasitic Worms
 About 50 species parasitize humansAbout 50 species parasitize humans
 Distributed in all areas of the worldDistributed in all areas of the world
 Yearly estimate of worldwide infections- inYearly estimate of worldwide infections- in
the billionsthe billions