The ProtistsChapter 22

2The ProtistsThe Protists

OutlineOutline

Protist BiologyProtist Biology

Protist EvolutionProtist Evolution

Protist DiversityProtist Diversity

Green AlgaeGreen Algae

Red AlgaeRed Algae

Brown AlgaeBrown Algae

DiatomsDiatoms

DinoflagellatesDinoflagellates

Protist Diversity, Protist Diversity, cont.cont.

EuglenoidsEuglenoids

ZooflagellatesZooflagellates

PseudopodsPseudopods

CiliatesCiliates

SporozoansSporozoans

Slime MoldsSlime Molds

Water MoldsWater Molds

3The ProtistsThe Protists

General Biology of the ProtistsGeneral Biology of the Protists

Classified into the Domain Eukarya & Classified into the Domain Eukarya & the Kingdom Protistathe Kingdom Protista

Morphology:Morphology:Most unicellularMost unicellularMany with amazingly high level of Many with amazingly high level of strucrural and functional complexitystrucrural and functional complexity

Life cycles:Life cycles:Asexual reproduction commonAsexual reproduction commonSexual reproduction may occur when Sexual reproduction may occur when conditions deteriorateconditions deteriorate

Some life cycles simple, many Some life cycles simple, many extremely complexextremely complex

4Origin of the Eukaryotic Cell

5The ProtistsThe Protists

Ecology of ProtistsEcology of ProtistsProtists are of enormous eco-logical Protists are of enormous eco-logical importanceimportance

Photoautotrophic forms:Photoautotrophic forms: Produce oxygenProduce oxygen Function as producers in both freshwater and Function as producers in both freshwater and saltwater ecosystemssaltwater ecosystems

Major component of planktonMajor component of plankton­ Organisms that are suspended in the waterOrganisms that are suspended in the water­ Serve as food for heterotrophic protists and Serve as food for heterotrophic protists and animalsanimals

Many protists are symbiontsMany protists are symbionts Ranges from strict parasitism to mutualismRanges from strict parasitism to mutualism Coral reefs greatly aided by symbiotic Coral reefs greatly aided by symbiotic photoautotrophic protists in tissues of coralsphotoautotrophic protists in tissues of corals

6The ProtistsThe Protists

Evolution of ProtistsEvolution of ProtistsComplexity and diversity of protists Complexity and diversity of protists makes them difficult to classifymakes them difficult to classify

Many classification schemes proposedMany classification schemes proposed

None has broad supportNone has broad support

Cannot be classified as plants, animals, or Cannot be classified as plants, animals, or fungifungi

Could be split into as many as a dozen Could be split into as many as a dozen kingdomskingdoms

The scheme chosen for this discussion is The scheme chosen for this discussion is based on modes of nutritionbased on modes of nutrition

7Protist Diversity

8The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Green Algae – The ChlorophytaGreen Algae – The Chlorophyta

Phylum ChlorophytaPhylum ChlorophytaApproximately 7,500 speciesApproximately 7,500 speciesInhabit a variety of environments including oceans, Inhabit a variety of environments including oceans, freshwater, snowbanks, tree bark, and turtles freshwater, snowbanks, tree bark, and turtles backsbacks

Many are symbionts with fungi, plants, or animalsMany are symbionts with fungi, plants, or animalsMorphology variedMorphology varied

Majority unicellular, but many are filamentous or Majority unicellular, but many are filamentous or colonialcolonial

Some are multicellular and resemble leaves of Some are multicellular and resemble leaves of lettuce lettuce

Plants thought to be derived from Chlorophyta Plants thought to be derived from Chlorophyta because both groups:because both groups: Have a cell wall that contains celluloseHave a cell wall that contains cellulose Possess chlorophylls a and b, andPossess chlorophylls a and b, and Store excess food as starchStore excess food as starch

9The ProtistsThe ProtistsGreen Algae:Green Algae:ChlamydomonasChlamydomonas

A minute (<25 A minute (<25 μμ m), actively moving flagellatem), actively moving flagellate

Inhabits still, freshwater poolsInhabits still, freshwater pools

Fossil ancestors date back over a billion yearsFossil ancestors date back over a billion years

Anatomy:Anatomy: Definite cell wallDefinite cell wall Single, large, cup-shaped chloroplastSingle, large, cup-shaped chloroplast Chloroplast with a pyrenoid where starch is Chloroplast with a pyrenoid where starch is synthesizedsynthesized

Many with a bright red eyespot, or stigma on Many with a bright red eyespot, or stigma on chloroplastchloroplast

Two long, whip-like flagellaTwo long, whip-like flagella­ Project from the anterior endProject from the anterior end

­ Operate with a breaststroke motionOperate with a breaststroke motion

10Electron Micrograph of Chlamydomonas

11The ProtistsThe ProtistsGreen Algae:Green Algae:ChlamydomonasChlamydomonas

Most often reproduces asexuallyMost often reproduces asexually As many as 16 daughter cells within parent cellAs many as 16 daughter cells within parent cell

Escape by digesting the parent cellEscape by digesting the parent cell

Occasionally reproduces sexually Occasionally reproduces sexually Gametes fuse to form a zygoteGametes fuse to form a zygote

Becomes a heavy-walled, resistant zygosporeBecomes a heavy-walled, resistant zygospore

­ Goes into a period of dormancyGoes into a period of dormancy

­ Upon germination produces four zoospores by Upon germination produces four zoospores by meiosismeiosis ““Spore” - a reproductive cell that develops into a Spore” - a reproductive cell that develops into a new organism without fusing with another cellnew organism without fusing with another cell

““Zoospore” - flagellated spores, typical of aquatic Zoospore” - flagellated spores, typical of aquatic speciesspecies

12Reproduction in Chlamydomonas

13The ProtistsThe ProtistsGreen Algae:Green Algae:SpirogyraSpirogyra

Filamentous green algaeFilamentous green algae

Found in green masses on the surfaces of Found in green masses on the surfaces of ponds and streamsponds and streams

Has ribbon-like, spiraled chloroplastsHas ribbon-like, spiraled chloroplasts

Sexual reproduction by conjugation:Sexual reproduction by conjugation: A temporary union during which the cells A temporary union during which the cells exchange genetic materialexchange genetic material

Two filaments line up parallel to each otherTwo filaments line up parallel to each other­ Cell contents of one filament move into the Cell contents of one filament move into the cells of the other filamentcells of the other filament

­ Forms diploid zygospores Forms diploid zygospores ­ In spring, undergo meiosis to produce new In spring, undergo meiosis to produce new haploid filamentshaploid filaments

14Spirogyra

15The ProtistsThe ProtistsGreen Algae:Green Algae:Multicellular FormsMulticellular Forms

UlvaUlvaMulticellular green algaMulticellular green alga

Commonly called sea lettuceCommonly called sea lettuce

Thallus (body) is two cells thickThallus (body) is two cells thick

Can be as much as a meter longCan be as much as a meter long

Sexual cycle involves alternation of Sexual cycle involves alternation of generations generations

Similar to higher plants, exceptSimilar to higher plants, except

­Both generations look exactly alike, andBoth generations look exactly alike, and

­ The gametes all look the sameThe gametes all look the same

16Multicellular Green Algae

17The ProtistsThe ProtistsGreen Algae:Green Algae:Colonial FormsColonial Forms

VolvoxVolvoxA colony is a loose association of independent A colony is a loose association of independent cellscells

A Volvox colony:A Volvox colony: A hollow sphereA hollow sphere Thousands of cells arranged in a single layer Thousands of cells arranged in a single layer surrounding a watery interiorsurrounding a watery interior

Each cell of colony resembles a Chlamydomonas Each cell of colony resembles a Chlamydomonas cellcell

Flagella beat in a coordinated fashionFlagella beat in a coordinated fashion Some cells are specialized for reproductionSome cells are specialized for reproduction­ Each can divide asexually to form a new daughter Each can divide asexually to form a new daughter colony within the parental colonycolony within the parental colony

­ Leaves parental colony by releasing an enzyme Leaves parental colony by releasing an enzyme that dissolves away a portion of the parental that dissolves away a portion of the parental colonycolony

18Volvox

19The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Red Algae – The RhodophytaRed Algae – The Rhodophyta

MulticellularMulticellular

About 5,000 speciesAbout 5,000 species

Live mostly in warmer seawater, some as Live mostly in warmer seawater, some as deep as 200 mdeep as 200 m

Economic ImportanceEconomic Importance Agar - capsules; dental impressions; Agar - capsules; dental impressions; cosmetics; culture medium; electrophoresis; cosmetics; culture medium; electrophoresis; food prep.food prep.

Carrageen - an emulsifying agent used in Carrageen - an emulsifying agent used in chocolate, low-fat foods, & cosmeticschocolate, low-fat foods, & cosmetics

The reddish-black wrappings around sushi The reddish-black wrappings around sushi rolls consist of processed Porphyra bladesrolls consist of processed Porphyra blades

20Red Algae

21The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Brown Algae – The PhaeophytaBrown Algae – The Phaeophyta

About 1,500 species About 1,500 species Most live in colder ocean waters along rocky Most live in colder ocean waters along rocky coastscoasts

No unicellular or colonial brown formsNo unicellular or colonial brown formsMorphology:Morphology:

Some small forms with simple filamentsSome small forms with simple filaments Others large multicellular forms that may Others large multicellular forms that may exceed 200 m in lengthexceed 200 m in length

Pigments:Pigments: Chlorophylls a and c Chlorophylls a and c Fucoxanthin (a type of carotinoid pigment) Fucoxanthin (a type of carotinoid pigment) gives them their colorgives them their color

Excess food stored as a carbohydrate called Excess food stored as a carbohydrate called laminarinlaminarin

22Brown Algae

23The ProtistsThe Protists

The PhaeophytaThe PhaeophytaMulticellular forms of green, red, and Multicellular forms of green, red, and brown algae are called seaweedsbrown algae are called seaweedsLaminariaLaminaria (a kelp), and (a kelp), and FucusFucus, , (rockweed), are common intertidal (rockweed), are common intertidal seaweedsseaweeds

NereocystisNereocystis and and MacrocystisMacrocystis often form often form forest-like thickets in deeper watersforest-like thickets in deeper waters

SargassumSargassum forms floating masses where forms floating masses where other organisms find shelterother organisms find shelter

Harvested for food and fertilizerHarvested for food and fertilizer

MacrocystisMacrocystis is source of algin, a is source of algin, a thickener for foodsthickener for foods

24The ProtistsThe Protists

The PhaeophytaThe PhaeophytaLaminariaLaminaria shows tissue differentiation shows tissue differentiation

Transport organic nutrients in a tissue Transport organic nutrients in a tissue resembling phloem resembling phloem

Life cycleLife cycle

Most brown algae have alternation of Most brown algae have alternation of generationsgenerations

In some species of In some species of FucusFucus

­Meiosis produces gametes instead of Meiosis produces gametes instead of sporesspores

­ The adult is always diploid, as in animalsThe adult is always diploid, as in animals

25The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Yellow-green Algae – The Yellow-green Algae – The ChrysophytaChrysophyta

Diatoms (formerly Bacillariophyta) are the Diatoms (formerly Bacillariophyta) are the most numerous unicellular algae in the most numerous unicellular algae in the oceansoceans

Significant portion of phytoplanktonSignificant portion of phytoplanktonCell wallCell wall

Two valves, with the larger valve acting as a Two valves, with the larger valve acting as a lid (like a mint tin)lid (like a mint tin)

Contains silicaContains silica

Diatomaceous earth used asDiatomaceous earth used as Filtering agentsFiltering agents Sound-proofing materialsSound-proofing materials Polishing abrasivesPolishing abrasives

26The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Dinoflagellates – The PyrrophytaDinoflagellates – The Pyrrophyta

About 4,000 species of unicellular aquatic and marine About 4,000 species of unicellular aquatic and marine organismsorganisms

Morphology:Morphology: Cell is usually bounded by protective cellulose plates Cell is usually bounded by protective cellulose plates impregnated with silicates impregnated with silicates

Typically with two flagellaTypically with two flagella­ One in a longitudinal groove with its distal end freeOne in a longitudinal groove with its distal end free­ The other lies in a transverse groove that encircles the The other lies in a transverse groove that encircles the

organismorganism

Symbiotic dinoflagellates in corals called zooxanthellaeSymbiotic dinoflagellates in corals called zooxanthellae Dinoflagellates provide their host with organic nutrientsDinoflagellates provide their host with organic nutrients Corals provide wastes that fertilize the algaeCorals provide wastes that fertilize the algae Some lack chloroplasts and are parasiticSome lack chloroplasts and are parasitic

Gymnodinium brevisGymnodinium brevis may cause “red tide” may cause “red tide” Produce a powerful neurotoxin that has caused massive fish Produce a powerful neurotoxin that has caused massive fish kills kills

Consume shellfish during outbreak can cause respiratory Consume shellfish during outbreak can cause respiratory paralysisparalysis

27 Diatoms and Dinoflagellates

28 Fish Kill and Dinoflagellate Bloom

29The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:The Euglenoids – Phylum The Euglenoids – Phylum EuglenophytaEuglenophyta

Small freshwater unicellular organismsSmall freshwater unicellular organisms

Difficult to classifyDifficult to classify

Have two flagella and an eyespot (shades a Have two flagella and an eyespot (shades a photoreceptor)photoreceptor) One flagellum much longer than the otherOne flagellum much longer than the other­ Projects out of an anterior, vase-shaped Projects out of an anterior, vase-shaped invaginationinvagination

­ Called a tinsel flagellum because of hair-like Called a tinsel flagellum because of hair-like projectionsprojections

Cell bounded by flexible pellicleCell bounded by flexible pellicle

Chloroplasts:Chloroplasts: Surrounded by three rather than two membranesSurrounded by three rather than two membranes With a pyrenoid which produces an unusual type With a pyrenoid which produces an unusual type of carbohydrate called paramylonof carbohydrate called paramylon

30 Euglen

a

31The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Zooflagellates – Phylum Zooflagellates – Phylum ZoomastigophoraZoomastigophora

Colorless heterotrophsColorless heterotrophsMost symbiotic and many parasiticMost symbiotic and many parasiticWell known for causing various diseases in Well known for causing various diseases in

humanshumans TrypanosomaTrypanosoma

­ African sleeping sickness - Tsetse flyAfrican sleeping sickness - Tsetse fly­ Chagas disease – Kissing bugChagas disease – Kissing bug

Giardia lambliaGiardia lamblia­ Most common flagellate in human digestive tractMost common flagellate in human digestive tract­ Causes severe diarrhea Causes severe diarrhea ­ Cysts are transmitted in contaminated waterCysts are transmitted in contaminated water­ Beavers are important reservoir hostsBeavers are important reservoir hosts

Trichomonas vaginalisTrichomonas vaginalis­ Sexually transmitted protist,Sexually transmitted protist,­ Infects urogenital organs; a common cause of Infects urogenital organs; a common cause of

vaginitisvaginitis

32 Zooflagellat

es

33 Giardia lamblia

34The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Protists with PseudopodsProtists with Pseudopods

Pseudopods form when cytoplasm streams Pseudopods form when cytoplasm streams forward in a particular directionforward in a particular direction

Amoeboids (phylum Rhizopoda) are protists Amoeboids (phylum Rhizopoda) are protists that move and ingest their food with that move and ingest their food with pseudopodspseudopods Phagocytize foodPhagocytize food

Entamoeba histolyticaEntamoeba histolytica - a parasite of the human - a parasite of the human colon; colon;

­ Causes amoebic dysenteryCauses amoebic dysentery

­ Can be fatalCan be fatal

Foraminiferans (phylum Foraminifera) and Foraminiferans (phylum Foraminifera) and radiolarians (phlyum Actinopoda)radiolarians (phlyum Actinopoda) Both have a skeleton (test) of either calcite or Both have a skeleton (test) of either calcite or silicasilica

35 Protists with Pseudopods

36The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:The Ciliates – Phylum CiliophoraThe Ciliates – Phylum Ciliophora

Ciliates (phylum Ciliophora) are among Ciliates (phylum Ciliophora) are among the most complex of the protozoansthe most complex of the protozoansHundreds of cilia beat in coordinated Hundreds of cilia beat in coordinated rhythmrhythm

Most are holozoic, swallowing food Most are holozoic, swallowing food wholewhole

Divide by transverse binary fission Divide by transverse binary fission during asexual reproductionduring asexual reproduction

Two nuclei of differing typesTwo nuclei of differing types

­Micronucleus – HeredityMicronucleus – Heredity

­Macronucleus – MetabolismMacronucleus – Metabolism

37 Ciliat

es

38The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:The Sporozoans – Phylum The Sporozoans – Phylum ApicomplexaApicomplexa

Nonmotile obligate parasitesNonmotile obligate parasites

Most serious parasitic disease of Most serious parasitic disease of human is malariahuman is malariaPlasmodium Plasmodium sppspp

­Kills 3,000,000 people each yearKills 3,000,000 people each year

­ Transmitted by mosquitoTransmitted by mosquito

ToxoplasmaToxoplasma

­Humans get from catsHumans get from cats

­Causes birth defects and mental Causes birth defects and mental retardation when pregnant mom exposedretardation when pregnant mom exposed

39 Life Cycle of Plasmodium vivax

40The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Slime MoldsSlime Molds

Plasmodial Slime Molds - Phylum Plasmodial Slime Molds - Phylum MyxomycotaMyxomycotaBody in the form of a plasmodiumBody in the form of a plasmodium

­Diploid, multinucleated, cytoplasmic massDiploid, multinucleated, cytoplasmic mass

­ Enveloped by a slimy sheathEnveloped by a slimy sheath

Eventually produces sporangium which in Eventually produces sporangium which in turn produces sporesturn produces spores

Cellular Slime Mold - Phylum AcrasiomycotaCellular Slime Mold - Phylum AcrasiomycotaBody in the form of individual amoeboid cellsBody in the form of individual amoeboid cells

Later aggregate into pseudoplasmodium Later aggregate into pseudoplasmodium which then forms sporangium & sporeswhich then forms sporangium & spores

41 Plasmodial Slime Molds

42The ProtistsThe ProtistsDiversity of Protists:Diversity of Protists:Water Molds - Phylum OomycotaWater Molds - Phylum Oomycota

Most live in the waterMost live in the water

Phylum name refers to the enlarged tips Phylum name refers to the enlarged tips (called oogonia) where eggs are produced(called oogonia) where eggs are produced

Body filamentous, appearing like true Body filamentous, appearing like true FungiFungiCell walls largely of cellulose rather than Cell walls largely of cellulose rather than chitinchitin

The organism is diploid (not haploid as in The organism is diploid (not haploid as in the fungi) the fungi)

Phytophthora infestansPhytophthora infestans caused the 1840’s caused the 1840’s potato famine in Irelandpotato famine in Ireland

SaprolegniaSaprolegnia is often seen as a white, is often seen as a white, cotton-like coating on dead aquarium fishcotton-like coating on dead aquarium fish

43Water Mold

44The ProtistsThe Protists

ReviewReview

Protist BiologyProtist Biology

Protist EvolutionProtist Evolution

Protist DiversityProtist Diversity

Green AlgaeGreen Algae

Red AlgaeRed Algae

Brown AlgaeBrown Algae

DiatomsDiatoms

DinoflagellatesDinoflagellates

Protist Diversity, Protist Diversity, cont.cont.

EuglenoidsEuglenoids

ZooflagellatesZooflagellates

PseudopodsPseudopods

CiliatesCiliates

SporozoansSporozoans

Slime MoldsSlime Molds

Water MoldsWater Molds

The ProtistsEnding Slide

Chapter 22