Eukaryotes
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•
•
•
•
Protista, Fungi, Plantae, Animalia
Complex
>10x larger
DNA in nucleus
Cell membrane
– Some also have cell wall
• Membrane bound organelles
– specialization
Protista
• Very diverse
• mostly unicellular, some colonial, some
multicellular (w/simple tissues)
• Autotrophs
– Plant-like
• Heterotrophs
– Animal-like protozoans
– Fungal-like
• Mixotrophs
– Photoautotrophic and heterotrophic pathways
• Aquatic or moist environments
Protistan origin
• Eukaryotes that share some Archaea characteristics
(e.g. biochemistry & genetics)
– Lacks the peptidoglycons in cell walls of bacteria
• Otherwise varies in modes of Eukarya reproduction,
locomotion, & morphology
• Endocytosis; 1o endosymbiosis with prokaryotes (Fig 28.2)
– 2o endosymbiosis: heterotroph engulfing red or green algae
“…protist phylogeny continues to emerge…
changing rapidly…”(Campbell 28.1)
• Five Supergroups:
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–
–
–
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Excavata
Chromalveolata
Rhizaria
Archaeplastida
Unikonta
Figure 28.3a
Parabasalids
Euglenozoans
Excavata
Diplomonads
Apicomplexans
Ciliates
Diatoms
Stramenopiles
Golden algae
Chromalveolata
Alveolates
Dinoflagellates
Brown algae
Oomycetes
Forams
Radiolarians
Green
algae
Chlorophytes
Charophytes
Land plants
Archaeplastida
Red algae
Rhizaria
Cercozoans
Gymnamoebas
Entamoebas
Opisthokonts
Nucleariids
Fungi
Choanoflagellates
Animals
Unikonta
Amoebozoans
Slime molds
“…it may be helpful to focus less on the specific names of
groups of organisms and more on why the organisms are
important…” (Campbell 28.1)
Functionally…
“Animal-like” Protozoans
heterotrophic consumers
“Fungi-like” Protists
share fungal characteristics; many
moved back/forth from Fungi
“Plant-like” Algae
non-plant, photosynthetic aquatic
eukaryotes
Diplomonads
(Excavata clade – 8 ed.)
– Spore forming
– Two nuclei
– Multiple flagella
– Usually anaerobic
• Due to their modified
mitochondria that lack ETCs &
the use of O2 in respiration
– E.g. Giardia
• Intestinal parasite
• Contaminates streams
• Causes severe diarrhea
Kinetoplastids
(Excavata clade – 8 ed.)
• Kinetoplast
– DNA in mitochondria
•
•
•
•
E.g. Trypanosoma
Blood parasite
Single encased flagellum
African Tsetse fly
– Sleeping sickness (attacks
nervous system; lethargy;
death if untreated)
• So.Amer. Kissing bugs
– Chagas disease
Amoeboids
• Pseudopodia
– extensions of the cell
• Locomotion
• Feeding
• Various environments
– Aquatic; parasitic;
moist soils
• Various morphology
Protozoans
• Animal-like protists
– Heterotrophs
– Unicellular or colonial
– Various forms
• Foraminiferans
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–
–
–
Have a CaCO3 shell
Thin extended pseudopods
Planktonic or benthic
Adds to the calcareous
sediments
• Radiolarians
– Silica shells; thin pseudopods;
planktonic; silicious sediments
• Ciliates
– Use of cilia to feed and move
– Stalked, colonial, or “freeswimming”
Ciliates
• Cilia to move and feed
– E.g. Paramecium,
Stentor, Vorticella
• Contractile vacuole
– osmoregulation
• Two nuclei types
– Macronucleus
• Everyday activities
– Micronuclei
• Sexual reproduction
Apicomplexans
• Parasites
• Apex structures for
penetrating host cells
• Lack cilia, flagella, or
pseudopods
• E.g. Plasmodium
– Malaria
– Enters and feeds on
red blood cells
– Vector = ♀ mosquitoes
Dinoflagellates
• Two flagella in grooves
– Spinning flagellates
• Phytoplankton
– Photosynthesizing
aquatic species
– Red tides
• red pigments along with
chl a
– Some are toxic
• Shell fish accumulation
– Bioluminescence
Diatoms
• Phytoplankton
• Silica cell wall
– Glass-like
– Two halves like a petri
plate
• Mitotically divide the
halves
• Secretes the smaller
half
• Nucleus triggers
meiosis when too small
Diatom reproduction
• Chrysophyta
– Silicoflagellates
• Star shaped; silicon
– Desmids
• Pectin & silican
walls
• Golden or yellow
• Coccolithorids
– Calcium carbonate
coccoliths
• All are important
planktonic 1o
producers
Emiliania huxleyi (E. huxleyi)
Multicellular Protists (algae)
• More photoautotrophic
protistans… known as:
– Algae, seaweed, kelp
– Thalli may be filamentous, grow in
mats or crusts, sheets, or kelp
• “ Plant-like” primary producers, but
not plants:
– Lack true leaves, stems & roots
• Organized by pigment variations
– Phaeophyta (browns)
– Rhodophyta (reds)
– Chlorophyta (greens)
Current phylogeny of the 5 supergroups of Eukaryotes
See also: Summary Table on page 598 of text (Ch 28)
Phaeophyta
• Brown/yellow pigment
– Fucxanthin, some phycobilin,
some carotenoids (& chl)
• Diverse morphologies
– Simple, small individual to large &
complex (i.e. lengths up to 100m)
• kelp forest communities
• Some exhibit rapid growth
– 1 to 2 feet a day
– Important source of algin
• Thickener, stabilizer, emulsifier in
many products
Rhodophyta
• Red pigments
– Phycoerythrin, Phycobilins,
carotenoids
• As a group, expands to greater
depths than other algae
– Why?
• Coralline algae
– CaCO3 in cell walls
• Defense and structure
• Important component of coral
reef environments
– Filamentous or Encrusting
• Important component of coral
reef environments
• Commercial uses
– Source of carrageenan & agar
(emulsifiers & gel thickeners)
• Food
– Nori (sushi wraps) from Porphyra
Chlorophyta
• Green pigments
– Chl a & Chl b
– Same as plants
• Diverse morphologies
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–
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Filamentous
Sheets
Spongy
Calcareous
• Important component of
coral reef environments
Other Chlorophytan examples
• Colonial
• plant-like
chloroplasts
– Volvox
– Ulothrix
– Spyrogyra