Download Protists

Origin and Diversification
of Eukaryotes: Protists
Eukaryotic Cells
 Nucleus and membrane bound organelles
 Well developed cytoskeleton – structural
support that lends to asymmetric forms
 May have originated more than 2.7 bya, but
1.8 bya widely accepted
3 stages of diversity documented
by fossil records
 Initial diversification – 1.8 – 1.3 bya
 Origin of multicellularity 1.3 bya – 635 mya
 Emergence of large eukaryotes 635-535 mya
endosymbiosis
 Symbiotic relationship in which one organism
lives inside the bosy or cell of another
organism.
 DNA sequence data suggest that eukaryotes
are “combination” organism from Archaea
and Bacteria
 Endosymbiont theory – mitochondria and
plastids were formerly small prokaryotes that
began living within larger cells. (See page 485)
Multicellularity
 Colonies – collection of cells that are
connected but show little or no cellular
differentiation.
 Multicellular organisms with differentiated
cells – Algae, plants, fungi and animals
Characteristics
 Most diverse kingdom
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eukaryotic., 1.5 bya
Primarily unicellular/multicellular,
heterotrophic/autotrophic
Usually asexual, some sexual
Found in water, damp soil and sand, leaf litter
Some are parasitic
14 phyla
Characteristics
 Characteristics first seen in Protista kingdom
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Sexual reproduction (varies, mitosis and
meiosis – usually in harsh enviro.)
Multicellularity (coordination among
specialized cells)
Complex flagella and cilia (as opposed to
simple seen in bacteria)
Protist diversity
 Heterotrophic protists = protozoans, slime
molds, water molds, parasites
 Photosynthetic protists = Algae
 Some are classified further by how they
move:
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Amoebas – pseudopodia
Ciliates – cilia, ex. paramecium
Flagellates – flagella, ex. Euglena
Algae – Green, Red and Brown
 Strict autotrophs, some multicellular
 Distinguished by type of pigment they contain
 Red
 Multicellular, warm ocean waters
 Red pigment can absorb light in deep water
 Brown
 Multicellular, marine
 Kelp, grows along coasts, food and shelter
 Green
 Most freshwater, uni and multicellular
 Contains chlorophyll a and b
Green Algae
 Phylum Chlorophyta
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Most unicellular, can be filamentous or
colonial
Chlamydomonas – unicellular green algae
Spirogyra – filamentous green algae
Ulva – multicellular green algae (sea lettuce)
Volvox – colonial (loose association of
independent cells) green algae
Red Algae/Brown Algae
 Phylum Rhodophyta
 Economically important –
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Agar
Wrappings around sushi
Emulsifying agent for production of chocolate
 Phylum Phaeophyta
 Contain chlorophylls a and c and carotinoid
 Kelp, rockweed – grow along shoreline
 Harvested for human food and fertilizers
 Algin – pectin-like material added to icecream
Diatoms
 Phylum Chrysophyta – includes golden-brown
algae and yellow-green algae
 Photosynthetic, significant part of phytoplankton,
Important to food chain
 Double shell made out of silica, like hat box
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Move by excreting chemicals through Diatomaceous
earth –
abrasives
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holes in shell
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 Found in oceans and lakes
Dinoflagellates
 2 flagella, cellulose plates
 Unicellular
 Most are marine, make up part of the
plankton, important food source, producers
 Some produce powerful toxins – “red tide”
Euglena
 Freshwater, unicellular with 2 flagella
 Some photosynthetic with chloroplasts and
has ability to ingest food as well
 Pellicle – protein fiber inside cell membrane,
allows for flexibility and shape change
 Eyespot – light sensitive organ, toward light
 Contractile vacuole –
expels excess water
Zooflagellates
 Mostly unicellular, hetertrophic protozoans
 Symbiotic and parasitic forms
 Trypanosomes – transmitted by tsetse fly
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Causes African Sleeping Sickness
 Giardia lamblia – cysts from contaminated
water, intestinal wall, severe diarrhea
 Trichomonas vaginalis – STO, infects vagina
and urethra of women, prostate of males
Amoeba
 Pseudopodia – false foot, cytoplasmic
extensions
 Food vacuole – food enters and moves
throughout cell
 Contractile vacuole – regulates water
 Entamoeba histolytica – amoebic dysentery
Forams
 marine protist that lives in sand or attaches to
other organisms
 Tests – porous shells
 Thin projections of cytoplasm extend through
pores and aid in swimming
Paramecium
 Freshwater streams and ponds
 Unicellular, heterotrophic
 Cilia to move
 Two nucluei
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Macro – cell activities, includes DNA
Micro –cell reproduction, contains
chromosomes
Sporozoans – parasitic protists
 Form spores during their reproductive cycle
 Nonmotile, spore forming, unicellular
parasites
 Malaria – anopheles mosquito, pg 392
 Toxoplasma gondii – toxoplasmosis,
during pregnancy,
can affect fetus
Slime molds - decomposers
 Cellular slime mold, small
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Behave like amoebas
Ingest bacteria
During stress, form multicellular colonies
 Plasmodial slime molds
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Mass of cytoplasm that looks like ooze,
colorful
Eat bacteria and other organic material,
phagocytes
Water Molds
 Filamentous decomposers
 Parasitic to plants and animals in ecosystems
 Cell wall contains cellulose, not chitin
 Usually have furry growths
 Responsible for potato famine in Ireland,
1840’s
Beneficial protists
 Commensal protists that live in digestive
tracts of humans and livestock (hay,
cellulose)
 Plankton – food, shelter, producers
 Largest group of photosynthesizers
 Abrasives
 Detritivores – recycle chemicals in
environment
 Symbiotic relationships - coral