ProtistansProtistans

Chapter 22Chapter 22

Protistans are Unlike Protistans are Unlike Prokaryotes Prokaryotes

Have a nucleus and organellesHave a nucleus and organelles Have proteins associated with DNAHave proteins associated with DNA Use microtubules in a cytoskeleton, Use microtubules in a cytoskeleton,

spindle apparatus, and cilia and spindle apparatus, and cilia and flagellaflagella

May contain chloroplastsMay contain chloroplasts May divide by mitosis and meiosisMay divide by mitosis and meiosis

Difficult to ClassifyDifficult to Classify

Historically a catch-all kingdomHistorically a catch-all kingdom Differ enormously from one another in Differ enormously from one another in

morphology and life-stylesmorphology and life-styles Molecular and biochemical comparisons Molecular and biochemical comparisons

are clarifying the evolutionary pictureare clarifying the evolutionary picture Protistans are not a monophyletic groupProtistans are not a monophyletic group

Evolutionary TreeEvolutionary Treebranch leading

to plants

brown algae

chrysophytes

oomycotes

Stramenopiles

charophytes

green algae

red algae

slime molds

parabasalids(e.g., Trichomonas)

diplomonads(e.g., Giardia)

Endosymbiotic origins from prokaryotic

ancestors

amoeboid protozoans

“crown” of eukaryotes (rapid divergences)

branch leading to fungi

branch leading to animals

Alveolates

ciliates

sporozoans

dinoflagellates

euglenoidskinetoplastids

?

Figure Figure 22.0222.02Page 366Page 366

Euglenoids: Euglenoids: Evolutionary PuzzleEvolutionary Puzzle

Some heterotrophsSome heterotrophs

Most have chloroplasts like green algae Most have chloroplasts like green algae

and plantsand plants

Have flagella like flagellated protozoansHave flagella like flagellated protozoans

Related to flagellated protozoansRelated to flagellated protozoans

Acquired chloroplasts by endosymbiosis Acquired chloroplasts by endosymbiosis

Figure 22.3Page 365

Euglenoid Body PlanEuglenoid Body Plan

pelliclemitochondrionGolgi body

ER

nucleuseyespot

long flagellum

contractile vacuole chloroplast

nucleus

Figure Figure 22.322.3Page 365Page 365

Euglenoids Are aEuglenoids Are aMonophyletic GroupMonophyletic Group

Members share a common Members share a common ancestor and derived traits that ancestor and derived traits that are present in no other groupare present in no other group

Unique traitsUnique traits

A storage carbohydrate A storage carbohydrate Type of eyespot Type of eyespot

Flagellated ProtozoansFlagellated Protozoans

Have one or more flagellaHave one or more flagella

All are heterotrophsAll are heterotrophs

EuglenoidsEuglenoids

Kinetoplastids (include trypanosomes)Kinetoplastids (include trypanosomes)

Parabasalids (include trichomonads)Parabasalids (include trichomonads)

Diplomonads (include Diplomonads (include GiardiaGiardia))

Trypanosomes Trypanosomes (Kinetoplastids)(Kinetoplastids)

free flagellum

basal body of flagellum

nucleus

mitochondrionundulating membrane

Trypanosoma bruceiTrypanosoma brucei causes African causes African sleeping sickness sleeping sickness

T. cruziT. cruzi causes Chagas disease causes Chagas disease Figure 22.4Page 368

Trichomonads Trichomonads (Parabasalids)(Parabasalids)

Trichomonas vaginalisTrichomonas vaginalis causes causes trichomoniasis, a sexually transmitted trichomoniasis, a sexually transmitted

disease disease

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Figure 22.5aPage 368

GiardiaGiardia (a Diplomonad) (a Diplomonad)

Internal parasite of humans, animalsInternal parasite of humans, animals

Survives outside of body as cystsSurvives outside of body as cysts

Ingested cysts release trophozoites that Ingested cysts release trophozoites that attach to intestinal liningattach to intestinal lining

Causes giardiasis Causes giardiasis

Amoeboid Protozoans Amoeboid Protozoans (Sarcodina)(Sarcodina)

Move by means of cytoplasmic Move by means of cytoplasmic streaming and pseudopodsstreaming and pseudopods

Naked amoebasNaked amoebas

Foraminiferans Foraminiferans

HeliozoansHeliozoans

Radiolarians Radiolarians

Rhizopods

Actinopods

Naked AmoebasNaked Amoebas

Change shape constantlyChange shape constantly

Most are free-living cells that engulf Most are free-living cells that engulf

their preytheir prey

Some are symbionts in animal gutsSome are symbionts in animal guts

A few are opportunistic pathogensA few are opportunistic pathogens

Other Amoeboid Other Amoeboid ProtozoansProtozoans

Foraminiferans Foraminiferans

Calcium carbonate Calcium carbonate

shellshell

Radiolarians and Radiolarians and

Heliozoans Heliozoans

Shells of silicaShells of silica

A living heliozoan

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Figure 22.6cPage 369

AlveolatesAlveolates

Have tiny, membrane-bound sacs Have tiny, membrane-bound sacs (alveoli) underneath their outer (alveoli) underneath their outer membranesmembranes

CiliatesCiliates

SporozoansSporozoans

DinoflagellatesDinoflagellates

Ciliates (Ciliphora)Ciliates (Ciliphora)

All heterotrophsAll heterotrophs

Arrays of cilia allow Arrays of cilia allow movement and direct movement and direct food into oral cavityfood into oral cavity

Diverse life-stylesDiverse life-styles

Hypotrich

Paramecium

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Figure 22.7cPage 370

Body Plan of Body Plan of ParameciumParamecium

food vacuole

food residues being ejected gullet cilia trichocysts (“harpoons”)

contractile vacuole filledmicronucleus

macronucleus

contractile vacuole emptied

Figure 22.7aPage 370

Ciliate ConjugationCiliate Conjugation

Most ciliates have two different nucleiMost ciliates have two different nuclei Large macronucleusLarge macronucleus

Smaller micronucleusSmaller micronucleus

Micronucleus participates in sexual Micronucleus participates in sexual

reproduction (conjugation)reproduction (conjugation) Partners exchange micronucleiPartners exchange micronuclei

SporozoansSporozoans

Parasitic Parasitic

Complete part of the life cycle inside Complete part of the life cycle inside specific cells of a host organismspecific cells of a host organism

Many have elaborate life cycles that Many have elaborate life cycles that require different hostsrequire different hosts

Many cause serious human diseaseMany cause serious human disease

CryptosporidiumCryptosporidium

Motile infective stage (sporozoite) Motile infective stage (sporozoite)

invades intestinal epithelium invades intestinal epithelium

Causes cramps, watery diarrheaCauses cramps, watery diarrhea

Commonly transmitted by water Commonly transmitted by water

contaminated with cystscontaminated with cysts

ToxoplasmaToxoplasma

Cysts may be ingested with raw or Cysts may be ingested with raw or undercooked meatundercooked meat

Exposure to cysts from cat fecesExposure to cysts from cat feces Symptoms are usually mild in people with Symptoms are usually mild in people with

normal immune functionnormal immune function Infection during pregnancy can kill or Infection during pregnancy can kill or

damage the embryodamage the embryo

MalariaMalaria

Most prevalent in tropical and Most prevalent in tropical and subtropical parts of Africasubtropical parts of Africa

Kills a million Africans each yearKills a million Africans each year

Caused by four species of Caused by four species of PlasmodiumPlasmodium

Transmitted by Transmitted by AnophelesAnopheles mosquitoes mosquitoes

PlasmodiumPlasmodium Life Cycle Life Cycle

sporozoites

merozoite

Male and femalegametocytes in blood

sporozoites

Gametes formin mosquito gut, combine to form zygotes

Offspring enter blood, cause malarial symptomsFigure 22.11

Page 373

DinoflagellatesDinoflagellates

Most are single photosynthetic cellsMost are single photosynthetic cells

Important component of phytoplanktonImportant component of phytoplankton

Each has two flagellaEach has two flagella

Algal bloom is population explosion of Algal bloom is population explosion of dinoflagellatesdinoflagellates

Pfiesteria piscicidaPfiesteria piscicida

Associated with large fish kills Associated with large fish kills Complicated life cycle Complicated life cycle Population explosions tied to water Population explosions tied to water

pollutionpollution

StramenopilesStramenopiles

Unique trait is one of their two flagella Unique trait is one of their two flagella has thin filaments projecting from ithas thin filaments projecting from it

Cells have four outer membranesCells have four outer membranes Include Include

OomycotesOomycotes ChrysophytesChrysophytes Brown algaeBrown algae

OomycotesOomycotes

Large egg cell forms inside oogoniumLarge egg cell forms inside oogonium Saprobic decomposers, parasites, Saprobic decomposers, parasites,

pathogens pathogens • • Water moldsWater molds

• • Downy mildewsDowny mildews

• • White rustsWhite rusts

• • PhytophthoraPhytophthora

PhytophthoraPhytophthora

Plant pathogensPlant pathogens

Phytophthora infestans Phytophthora infestans Late blight of potatoes Late blight of potatoes

Phytophtora ramorumPhytophtora ramorumSudden oak death Sudden oak death

Figures 22.14, 22.15

Page 375

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Chrysophytes Chrysophytes (Chrysophyta)(Chrysophyta)

Mainly free-living photosynthetic cellsMainly free-living photosynthetic cells

Contain chlorophylls Contain chlorophylls aa, , cc11, and , and cc22

Four groups:Four groups:

- Golden algae - Diatoms- Golden algae - Diatoms

- Yellow-green algae - Coccolithophores- Yellow-green algae - Coccolithophores

DiatomsDiatoms

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Figure 22.16cPage 376

Major component of Major component of the phytoplanktonthe phytoplankton

Silica shell of two Silica shell of two overlapping partsoverlapping parts

Sediments rich in Sediments rich in diatom remains diatom remains quarriedquarried for many for many usesuses

CoccolithophoresCoccolithophores

Major component of Major component of the phytoplanktonthe phytoplankton

Calcium carbonate Calcium carbonate shellshell

Remains in chalk Remains in chalk and limestone and limestone depositsdeposits

Coccolithophore shell

Fig. 22.16d,ePage 376

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Brown Algae Brown Algae (Phaeophyta)(Phaeophyta)

1,500 species 1,500 species Most abundant in temperate Most abundant in temperate

seasseas Contain chlorophylls Contain chlorophylls aa and and cc, ,

and fucoxanthinand fucoxanthin Range in size from tiny Range in size from tiny

filaments to giant kelps filaments to giant kelps

Figure 22.17 Page 377

Macrocystis

Green Algae Green Algae (Chlorophyta)(Chlorophyta)

7,000 species 7,000 species

Resemble plantsResemble plants

Chlorophylls Chlorophylls aa and and bb

Starch grains in chloroplastsStarch grains in chloroplasts

Cell walls of cellulose, Cell walls of cellulose,

pectinspectinsUlva

Fig. 22.18Page 378

Red Algae (Rhodophyta)Red Algae (Rhodophyta)

4,100 species 4,100 species

Most abundant in tropical seasMost abundant in tropical seas

Can grow at great depths (phycobilins)Can grow at great depths (phycobilins)

Complex life cycles may include very Complex life cycles may include very different formsdifferent forms

Plasmodial Slime MoldsPlasmodial Slime Molds

MyxomycotaMyxomycota

Cell walls break down during Cell walls break down during

aggregation aggregation

Plasmodium migrates, then Plasmodium migrates, then

differentiates to form spore-differentiates to form spore-

bearing structuresbearing structures