Introduction to Protists

First eukaryotic organism thought to have evolved about 1.5 billion years ago Protozoans possible evolved from the 1 st 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 Eukaryotes Eukaryotic 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 have membrane-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 Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell B C D A N N N 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 Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell N N N N

Endosymbiosis Hypothesis C Some primitive prokaryotes also ingested cyanobacteria, which contain photosynthetic pigments A B C D Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell N N N N

Endosymbiosis Hypothesis D Cyanobacteria became chloroplasts, unable to live on their own A B C D Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell N N N N

Secondary Endosymbiosis and Origin of Algal Diversity Algae AB Heterotroph C N N Secondary endosymbiosis N Many membrane layers Algae ABC

Fig Cyanobacterium Heterotrophic eukaryote Over the course of evolution, this membrane was lost. Red alga Green alga Primary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis 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 Monera prokaryotic eukaryotic

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 floor

Phylum Ciliophora (“ciliates”) Largest, most homogeneous Share few characteristics with others Movement coordinated Sex: 8 mating types Animal-like Protists 8,000 species

Paramecium

Asexual reproduction Binary fission

Paramecium reproduction 1. Individuals fuse 2. Micronucleus produces 4 haploid nuclei

Paramecium reproduction 4. Mates swap micronuclei 3. One divides by mitosis, 3 disintegrate

Paramecium reproduction 5. Syngamy occurs, micronuclei fuse 6. Micronuclei undergo mitosis and form 8 micronuclei

Paramecium reproduction 7. Original macronucleus disintegrates; 4 micronuclei dev into new macronuclei 8. After 2 cell divisions w/out nuclear division, the new macro and micronuclei are parceled out into 4 new individuals

Phylum Zoomastigophora (“zooflagellates”) Move using flagella Move using flagella:1 to thousands of flagella Some parasites African trypanosomiasis – sleeping sickness – tsetse flyAfrican trypanosomiasis – sleeping sickness – tsetse fly Chagas Disease – kissing bugChagas Disease – kissing bug Leishmaniasis – sand flyLeishmaniasis – sand fly giardiasisgiardiasis Vaccines? change protein coat! Gave rise to animals? Animal-like Protists 1,500 species

African sleeping sickness Tsetse fly Trypansoma

The Kissing Bug Chagas disease

Leishmaniasis Sand fly Leishmania

Malaria Mosquito & “victim” Africa = kills 1 million children per year Thousands of sporozoites injected Vaccine? (US support?) Anopheles Mosquito Plasmodium sporozoite gameteocyte

Plasmodium, the parasite that causes malaria, spends part of its life in mosquitoes and part in humans.

Travel to Malarial Infected Areas

Malaria Prevention Quinine DEET Netting Genetically modified fungus

Fungus-like Protists Phylum Oomycota (“water molds”; mildew, blights) Some unicellular; others consist of hyphae Decomposers,parasites Cell walls- cellulose Related to algae based on cell wall composition Named after reproductive method 475 species No “septa”

water molds

Downy Mildew

Mildew hyphae

Oomycota Reproduction: the “egg fungi”, a relatively large egg cell is fertilized by a smaller “sperm nucleus,” forming a resistant zygote.

Fungus-like Protists Phylum Myxomycota (“slime molds”) Bizarre Bright colors Moving “slime” mass Acellular body 550 species

Fungus-like Protists 475 species Downey mildew Slime molds Mildew Water molds Blights

Slime Mold Maze The slime mold starts out evenly spread through the maze, but when food sources are placed at two ends, the slime mold retracts from everywhere but the shortest path.

The Blob Unidentified Growing Object “Big as a platter, foamy and creamy and pale yellow.” Died of sunstroke and nicotine poisoning

Plasmabot

cellular slime molds

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

HAB (harmful algal blooms) can result in PSP (paraletic shellfish poisoning) Gonyaulax polyhedra, Gymnodium

The numbers are representative values of the concentration in the tissues of dinoflagellate toxin (ppm) Primary producers Primary consumers Secondary consumers Tertiary consumers 0.04 ppm 0.23 ppm 2.07 ppm 13.8 ppm

Plant-like Protists Phylum Chrysophyta (“diatoms & golden algae”) Link to green algae 13,000 species

Diatom - Akashiwo sanguinea Domoic acid 2009 Washington State 10,000 seabirds deaths Alfred Hitchkock “The Birds” HAB- diatoms

epithecate hypothecate Diatom Reproduction- asexual auxospore Discards shell and grows new one

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 polyphyllum Sargassum echinocarpum Phaeophyta: Brown Algae Turbinaria ornata Padina japonica Hydroclathrus clathratus

Division Rhodophyta “Red algae” Most in marine habitats 4,000 species

Hypnea chordacea Asparagopsi s 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.What threat do alien algae pose? 3.What is PSP? 4.What is biomagnification? 5.Identify 2 autotrophic bacteria.