Kingdom Protozoa 1 The Protozoans Ciliates Amoeboid Protozoans Flagellated Protozoans.
Introduction to Protists. First eukaryotic organism thought to have evolved about 1.5 billion years...
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Transcript of Introduction to Protists. First eukaryotic organism thought to have evolved about 1.5 billion years...
Introduction to Protists
• First eukaryotic organism thought to have evolved about 1.5 billion years ago
• Protozoans possible evolved from the 1st eukaryotes by Endosymbiosis
• Endosymbiosis – process where one prokaryote lives inside another becoming dependent upon each other
Origin of Eukaryotes
• Membrane-bound nucleus and organelles
• Chromosomes consist of DNA and histone proteins and occur in pairs.
• Protists, fungi, plants & animals are composed of eukaryotic cells.
Origin of EukaryotesEukaryotic cell more complex than prokaryotic cell:
Prokaryotic Cells
Typical Animal Cell
Eukaryotic Animal Cell
Typical Plant Cell
Eukaryotic Plant Cell
Animal
Plant
mitochondria
chloroplasts
vacuole
Vacuole Functions• Storage• Support• Water Regulation
Both cell types havemembrane-bounded organelles
Infolding of membrane system forming nucleus and ER
Origin of Eukaryotes
Endomembrane infolding
Origin of Eukaryotes
Evolution of eukaryotic cell- Endosymbiosis
• Theory proposed by Mereschkovsky and refines by Margulis- serial endosymbiosis• Mitochondria and plastids were
prokaryotes that invaded larger cells• Endosymbiont, ancestral
mitochondria:Aerobic, heterotrophic &
prokaryotic
Origin of Eukaryotes
• Ancestral chloroplasts were photosynthetic, prokaryotes that became endosymbionts
• Relationship began as parasitic or undigested prey
• Assumed here that endomembrane infolding evolved first, i.e., cell already evolved nucleus, ER, …
Endosymbiosis Hypothesis
A
A prokaryote ingested some aerobic bacteria. The aerobes were protected and produced energy for the prokaryote
ChloroplastsAerobic bacteria MitochondriaCyanobacteria
Prokaryote
Animal Cell
Plant cell
B C D
A
N
NN
N
Endosymbiosis Hypothesis
B Over a long period of time the aerobes became mitochondria, no longer able to live on their own
A B C D
ChloroplastsAerobic bacteria MitochondriaCyanobacteria
Prokaryote
Animal Cell
Plant cellN
NN
N
Endosymbiosis Hypothesis
C Some primitive prokaryotes also ingested cyanobacteria, which contain photosynthetic pigments
A B C D
ChloroplastsAerobic bacteria MitochondriaCyanobacteria
Prokaryote
Animal Cell
Plant cellN
NN
N
Endosymbiosis HypothesisD Cyanobacteria became chloroplasts,
unable to live on their own
A B C D
ChloroplastsAerobic bacteria MitochondriaCyanobacteria
Prokaryote
Animal Cell
Plant cellN
NN
N
Secondary Endosymbiosis and Origin of Algal Diversity
Algae AB
Heterotroph C
N
N
Secondary endosymbiosis
N
Many membrane layers
Algae ABC
Fig. 28-02-2
Cyanobacterium
Heterotrophiceukaryote
Over the courseof evolution,this membranewas lost.
Red alga
Green alga
Primaryendosymbiosis
Secondaryendosymbiosis
Secondaryendosymbiosis
Secondaryendosymbiosis
Plastid
Dinoflagellates
Apicomplexans
Stramenopiles
Plastid
Euglenids
Chlorarachniophytes
Secondary Endosymbiosis
LUCA model places the archaea as more closely related to eukaryotes than they are to prokaryotes.
• All three domains seem to have genomes that are chimeric mixes of DNA that was transferred across the boundaries of the domains.
Common ancestral community of primitive cells model
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 28.8
Excavata
Chromalveolata
Rhizaria
Archaeplastida
Unikonta
Five Supergroups
Red and green algae
Slime molds
Forams and radiolarians
Dinoflagellates, diatoms, golden and brown algae
Euglenoids
Kingdom Protista
Plantae Fungi Animalia
Protista
Moneraprokaryoticprokaryotic
eukaryoticeukaryotic
Kingdom Protista
• Eukaryotic
• Mostly unicellular
• A very heterogeneous group include both heterotrophic and photoautotrophic forms
• 11 phyla
• Lots of disagreements
• Whittaker = “leftovers”
• binary fission splits into two asexually
• multiple fission producing more than two individuals
• sexually by conjugation (opposite mating strains join & exchange genetic material)
Reproduction:
3 informal groups
Animal-like protists
Fungus-like protists
Plant-like (algal) protists
Misleading: some change
Kingdom Protista
~ 45,000 species
Ciliophora
Kingdom Animalia
Sarcomastigophora
Apicomplexa
Mastigophora
Euglenophyta
Kingdom Plantae
Chrysophyta
Pyrrophyta
Myxomycota
Kingdom Fungi
Kingdom Protista
Chlorophyta
Phaeophyta
Rhodophyta
Amoeba
Cilliates
Flagellates
Animal-like Protists
13,000 species
• Classified by the way they move
Animal-like Protists
cilia flagella pseudopodia
• Heterotrophs ingest small food particles & digest it inside food vacuoles containing digestive enzymes
Animal-like protists
• Sarcomastigophora (amoebas, forams, radiolarian)
• Ciliophora (paramecium)
• Zoomastigophora (trypansoma)
• Apicocomplexa (Sporozoa)
Phylum Sarcomastigophora
“Amoeba”
Shell-like glass or calcium carbonate structures
Radiating projections
Animal-like Protists
13,000 species
Note: glass projections
Foraminifera
Tropics = beaches
Most have symbiotic algae
Foramenifera:Globigerina ooze
Covers about 36%of the ocean floorCovers about 36%of the ocean floor
Phylum Ciliophora (“ciliates”)
Largest, most homogeneous
Share few characteristicswith others
Movement coordinated
Sex: 8 mating types
Animal-like Protists
8,000 species
Paramecium
Plant-like Protists
• Dinoflagellates• Diatoms• Euglena• Cocolithophore• Green algae• Brown Algae• Red algae
Diatoms
Dinoflagellates
Radiolarian
Cocolithophore
Plant-like Protists
Phylum Pyrrophyta (“dinoflagellates”)
1,100 species
Cause “red tide”
Some live in corals
Marine and Freshwater
Zooxanthellae in Coral Polyp
Pyrocystis fusiformis
Bioluminescence
Plant-like ProtistsPhylum Chrysophyta (“diatoms &
golden algae”)
Link to green algae
13,000 species
Phylum Euglenophyta (“euglenoids”)
Plant-like Protists
800 species
Division Chlorophyta
“Green algae”
Most freshwater or terrestrial
Some marine
7,000 species
Halimeda opuntia
Chlorophyta: Green Algae
Caulerpa racemosa
Caulerpa sertularioides
Dictyosphaeria cavernosa
Codium edule
Division Phaeophyta
“Brown algae”
Marine habitats
Example: giant kelp forests
1,500 species
Example of complex morphology: Macrocystis
a. holdfast - attaches to substrate
b. stipe
c. blade - main organ of photosynthesis
d. bladder - keeps blades near the surface
Blade
Bladder
Stipe
Holdfast
Laminaria Life Cycle
Sargassum polyphyllumSargassum echinocarpum
Phaeophyta: Brown Algae
Turbinaria ornata
Padina japonicaHydroclathrus clathratus
Division Rhodophyta
“Red algae”
Most in marine habitats
4,000 species
Hypnea chordacea
Asparagopsis taxiformis
Galaxaura fastigiata
Acanthophora spicifera
Ahnfeltia concinna
Rhodophyta: Red Algae
Halimeda opuntia
Acanthophora
Avrainvillae
Eucheuma
Gracilaria Hypnea
Kappaphycus
Super Sucker
Inquiry
1. Identify 2 organisms that have a mutualistic symbiotic relationship with an other organism.
2. Read pages 510 – 514 Chpt 20
3. Alternation of Generations ( two examples)