eukaryotic cell components
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““KingdomKingdom”” Protista Protista –– Tracing Tracing Early Eukaryotic EvolutionEarly Eukaryotic Evolution
• The eukaryotic cell• Where did the first eukaryotes come from?• The “kingdom” Protista• Review of some protists• Origins of multicellularity
The Eukaryotic cellThe Eukaryotic cell
Paramecium, a ciliated protozoan
This view is under Nomarski phase contrast
Eukaryotic cell componentsEukaryotic cell components•• Cell wall (optional)Cell wall (optional)•• Plasma membranePlasma membrane•• Cytoplasm containing organelles:Cytoplasm containing organelles:
** Nucleus Nucleus –– DNA in chromosomesDNA in chromosomes** Other membraneOther membrane--bound organellesbound organelles
•• MitochondriaMitochondria•• Chloroplasts (optional)Chloroplasts (optional)
** RibosomesRibosomes** Membrane systemMembrane system
•• Flagella (optional)Flagella (optional)
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Eukaryotic vs. prokaryotic cellsEukaryotic vs. prokaryotic cells
• Size* Prokaryotes ≤ 10 µm* Eukaryotes ≥ 10 µm
• Complexity* Prokaryotes – simple* Eukaryotes – complex
• Location of chromosomes* Prokaryotes – free in cytosol* Eukaryotes – within a nucleus
• Flagellar mechanisms differ
Bacteria & Archeaprotists, Fungi, Plants, Animals
Bacterium (prokaryote)
Animal (eukaryote)
Plant (eukaryote)
(Actual size relative to eukaryotes below)
Life Life CyclesCycles some fungi
effectively have (c)
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Evolution of First Eukaryote(s)Evolution of First Eukaryote(s)• Forces leading to eukaryote
* Increases in size* Increases in complexity
• Mechanisms* Infolding of cell membrane* Serial endosymbiosis of
membrane-bound organelles
ProtistaProtista as a single as a single ““kingdomkingdom””-- CharacteristicsCharacteristics
• Eukaryotic• “Simple” – single cells, simple colonies• Reproduction varies• Includes all Eukaryotes that are NOT plants,
fungi, or animals• Polyphyletic – a “wastebasket” category
protists are probably many protists are probably many KingdomsKingdoms
• All the Eukaryotic groups arranged phylogenetically
You do not need to know these, You do not need to know these, just give examplesjust give examples
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Protists:Protists:Functional gFunctional groupsroups
• Algae – photosynthetic• Protozoa – non photosynthetic, consumers• Fungus-like Protists – nonphotosynthetic,
hyphal
• Each group itself is polyphyletic
ProtozoaProtozoa• Animal-like• Heterotrophic by ingestion• Motile
* pseudopodia – amoebas* flagella – flagellates* cilia – ciliates
Pseudopodial movement in Pseudopodial movement in AmoebaAmoeba
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AmoebaAmoeba engulfing preyengulfing prey
Fig 28.26
FlagellatesFlagellates
Giardia
FlagellatesFlagellates Trypanosome – cause of African Sleeping Sickness (Tsetse fly)
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ParameciumCiliatesCiliates
Macronucleusw/ micronuclei
behind
Oral groove on surface
Site of cell “anus”
Food vacuoles
Cilia
Undulating membrane in groove (ciliary)
Contractile vacuoles
Food particles
Paramecium, a ciliated protozoan
AlgaeAlgae
• Plant-like• Photosynthetic autotrophs• Diverse morphology
* Single cells, filaments, colonies, thalli
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Green AlgaeGreen Algae
Spirogyra
(with friend)
RedRed AlgaeAlgae
Bonnemaisonia
Brown AlgaeBrown Algae
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Other Other ““AlgaeAlgae””Euglena Diatoms
GoldenDinoflagellate
RED TIDERED TIDE
FungusFungus--like Protistalike Protista
• ± Tubular• Hetertrophic by absorption• Polyphyletic
* Slime molds* Water molds
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PlasmodialPlasmodial slime moldsslime molds
Slime stage
Sporangia
Cellular slime moldsCellular slime molds
See Fig 28.30
““EggEgg”” water water moldsmolds
hyphae
Motile, asexual spores
Sexual cycle
Fig 28.16
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Ecology of the ProtistsEcology of the Protists
• Though small, play major (keystone?) roles* 65 % of earth’s net primary production
(phytoplankton)* Microfeeders of bacteria, other protists* Food for larger plankton & animals* Habitats for other organisms* Decomposers* Parasites of plants and animals
Multicellularity Multicellularity --coloniescolonies
•• All cells the sameAll cells the same•• No differentiation in functionNo differentiation in function•• Cooperation Cooperation ☺☺
** VolvoxVolvox** Filaments are a kind of colonyFilaments are a kind of colony
•• May provide May provide ““buoyancybuoyancy””
Multicellularity Multicellularity --complex bodiescomplex bodies
•• Differentiation of tissues, organsDifferentiation of tissues, organs** Allows larger bodiesAllows larger bodies** Division of laborDivision of labor** Requires more complex developmentRequires more complex development
•• Several timesSeveral times** Seaweeds Seaweeds –– 3 lines, one to plants3 lines, one to plants** FungiFungi** AnimalsAnimals
Kelp forest