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Protistans. Chapter 22. Protistans are Unlike Prokaryotes . Have a nucleus and organelles Have proteins associated with DNA Use microtubules in a cytoskeleton, spindle apparatus, and cilia and flagella May contain chloroplasts May divide by mitosis and meiosis. Difficult to Classify.

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protistans

Protistans

Chapter 22

protistans are unlike prokaryotes
Protistans are Unlike Prokaryotes
  • Have a nucleus and organelles
  • Have proteins associated with DNA
  • Use microtubules in a cytoskeleton, spindle apparatus, and cilia and flagella
  • May contain chloroplasts
  • May divide by mitosis and meiosis
difficult to classify
Difficult to Classify
  • Historically a catch-all kingdom
  • Differ enormously from one another in morphology and life-styles
  • Molecular and biochemical comparisons are clarifying the evolutionary picture
  • Protistans are not a monophyletic group
evolutionary tree
Evolutionary Tree

branch leading to plants

branch leading to fungi

branch leading to animals

charophytes

green algae

amoeboid protozoans

Stramenopiles

Alveolates

red algae

brown algae

ciliates

chrysophytes

sporozoans

oomycotes

?

dinoflagellates

“crown” of eukaryotes (rapid divergences)

slime molds

euglenoids

kinetoplastids

parabasalids

(e.g., Trichomonas)

diplomonads

(e.g., Giardia)

Endosymbiotic origins from prokaryotic ancestors

Figure 22.02Page 366

euglenoids evolutionary puzzle
Euglenoids: Evolutionary Puzzle
  • Some heterotrophs
  • Most have chloroplasts like green algae and plants
  • Have flagella like flagellated protozoans
  • Related to flagellated protozoans
  • Acquired chloroplasts by endosymbiosis
euglenoid body plan
Euglenoid Body Plan

Figure 22.3

Page 365

long flagellum

contractile vacuole

chloroplast

eyespot

nucleus

nucleus

ER

Figure 22.3Page 365

Golgi body

mitochondrion

pellicle

euglenoids are a monophyletic group
Euglenoids Are aMonophyletic Group
  • Members share a common ancestor and derived traits that are present in no other group
  • Unique traits
    • A storage carbohydrate
    • Type of eyespot
flagellated protozoans
Flagellated Protozoans
  • Have one or more flagella
  • All are heterotrophs
  • Euglenoids
  • Kinetoplastids (include trypanosomes)
  • Parabasalids (include trichomonads)
  • Diplomonads (include Giardia)
trypanosomes kinetoplastids
Trypanosomes (Kinetoplastids)

undulating membrane

mitochondrion

basal body

of flagellum

free flagellum

nucleus

  • Trypanosoma brucei causes African sleeping sickness
  • T. cruzi causes Chagas disease

Figure 22.4Page 368

trichomonads parabasalids
Trichomonads (Parabasalids)

Trichomonas vaginalis causes trichomoniasis, a sexually transmitted disease

Do not post photos on Internet

Figure 22.5aPage 368

giardia a diplomonad
Giardia (a Diplomonad)
  • Internal parasite of humans, animals
  • Survives outside of body as cysts
  • Ingested cysts release trophozoites that attach to intestinal lining
  • Causes giardiasis
amoeboid protozoans sarcodina
Amoeboid Protozoans (Sarcodina)
  • Move by means of cytoplasmic streaming and pseudopods
  • Naked amoebas
  • Foraminiferans
  • Heliozoans
  • Radiolarians

Rhizopods

Actinopods

naked amoebas
Naked Amoebas
  • Change shape constantly
  • Most are free-living cells that engulf their prey
  • Some are symbionts in animal guts
  • A few are opportunistic pathogens
other amoeboid protozoans
Other Amoeboid Protozoans
  • Foraminiferans
    • Calcium carbonate shell
  • Radiolarians and Heliozoans
    • Shells of silica

A living heliozoan

Do not post photos on Internet

Figure 22.6cPage 369

alveolates
Alveolates
  • Have tiny, membrane-bound sacs (alveoli) underneath their outer membranes
  • Ciliates
  • Sporozoans
  • Dinoflagellates
ciliates ciliphora
Ciliates (Ciliphora)
  • All heterotrophs
  • Arrays of cilia allow movement and direct food into oral cavity
  • Diverse life-styles

Do not post photos on Internet

Paramecium

Figure 22.7cPage 370

Hypotrich

body plan of paramecium
Body Plan of Paramecium

food vacuole

food residues being ejected

gullet

cilia

trichocysts (“harpoons”)

contractile vacuole emptied

contractile vacuole filled

micronucleus

macronucleus

Figure 22.7aPage 370

ciliate conjugation
Ciliate Conjugation
  • Most ciliates have two different nuclei
    • Large macronucleus
    • Smaller micronucleus
  • Micronucleus participates in sexual reproduction (conjugation)
    • Partners exchange micronuclei
sporozoans
Sporozoans
  • Parasitic
  • Complete part of the life cycle inside specific cells of a host organism
  • Many have elaborate life cycles that require different hosts
  • Many cause serious human disease
cryptosporidium
Cryptosporidium
  • Motile infective stage (sporozoite) invades intestinal epithelium
  • Causes cramps, watery diarrhea
  • Commonly transmitted by water contaminated with cysts
toxoplasma
Toxoplasma
  • Cysts may be ingested with raw or undercooked meat
  • Exposure to cysts from cat feces
  • Symptoms are usually mild in people with normal immune function
  • Infection during pregnancy can kill or damage the embryo
malaria
Malaria
  • Most prevalent in tropical and subtropical parts of Africa
  • Kills a million Africans each year
  • Caused by four species of Plasmodium
  • Transmitted by Anopheles mosquitoes
plasmodium life cycle
Plasmodium Life Cycle

sporozoites

sporozoites

Gametes form

in mosquito gut,

combine to form

zygotes

merozoite

Offspring enter blood, cause malarial symptoms

Male and female

gametocytes

in blood

Figure 22.11Page 373

dinoflagellates
Dinoflagellates
  • Most are single photosynthetic cells
  • Important component of phytoplankton
  • Each has two flagella
  • Algal bloom is population explosion of dinoflagellates
pfiesteria piscicida
Pfiesteria piscicida
  • Associated with large fish kills
  • Complicated life cycle
  • Population explosions tied to water pollution
stramenopiles
Stramenopiles
  • Unique trait is one of their two flagella has thin filaments projecting from it
  • Cells have four outer membranes
  • Include
    • Oomycotes
    • Chrysophytes
    • Brown algae
oomycotes
Oomycotes
  • Large egg cell forms inside oogonium
  • Saprobic decomposers, parasites, pathogens

• Water molds

• Downy mildews

• White rusts

• Phytophthora

phytophthora
Phytophthora
  • Plant pathogens
  • Phytophthora infestans

Late blight of potatoes

  • Phytophtora ramorum

Sudden oak death

Do not post photos on Internet

Figures 22.14,

22.15Page 375

chrysophytes chrysophyta
Chrysophytes (Chrysophyta)
  • Mainly free-living photosynthetic cells
  • Contain chlorophylls a, c1, and c2
  • Four groups:

- Golden algae - Diatoms

- Yellow-green algae - Coccolithophores

diatoms
Diatoms
  • Major component of the phytoplankton
  • Silica shell of two overlapping parts
  • Sediments rich in diatom remains quarriedfor many uses

Do not post on Internet

Figure 22.16cPage 376

coccolithophores
Coccolithophores
  • Major component of the phytoplankton
  • Calcium carbonate shell
  • Remains in chalk and limestone deposits

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Coccolithophore shell

Fig. 22.16d,ePage 376

brown algae phaeophyta
Brown Algae (Phaeophyta)
  • 1,500 species
  • Most abundant in temperate seas
  • Contain chlorophylls a and c, and fucoxanthin
  • Range in size from tiny filaments to giant kelps

Macrocystis

Figure 22.17 Page 377

green algae chlorophyta
Green Algae (Chlorophyta)
  • 7,000 species
  • Resemble plants
    • Chlorophylls a and b
    • Starch grains in chloroplasts
    • Cell walls of cellulose, pectins

Ulva

Fig. 22.18Page 378

red algae rhodophyta
Red Algae (Rhodophyta)
  • 4,100 species
  • Most abundant in tropical seas
  • Can grow at great depths (phycobilins)
  • Complex life cycles may include very different forms
plasmodial slime molds
Plasmodial Slime Molds
  • Myxomycota
  • Cell walls break down during aggregation
  • Plasmodium migrates, then differentiates to form spore-bearing structures
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