Protistans Chapter 22. Protistans are Unlike Prokaryotes Have a nucleus and organelles Have...
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Transcript of Protistans Chapter 22. Protistans are Unlike Prokaryotes Have a nucleus and organelles Have...
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