Protists

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Protists

• Chapter 28

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Protists

• Eukaryotes
• Not plants, fungi or animals

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Protists

• Unicellular
• Colonial Multi-cellular
• Highly variable
• No one unifying feature
• protist informal term
• Greatest diversity of eukaryotic kingdoms.

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Endosymbiosis
Plastid
Dinoflagellates
Secondary endosymbiosis
Apicomplexans
Red alga
Cyanobacterium
Primary endosymbiosis
Stramenopiles
Plastid
Heterotrophic eukaryote
Secondary endosymbiosis
Over the course of evolution, this membrane was
lost.
Euglenids
Secondary endosymbiosis
Green alga
Chlorarachniophytes
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General biology

• Cell surface
• Locomotion organelles
• Cyst formation
• Nutrition
• Reproduction

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Cell surface

• Varies
• Only cell membrane
• Extra cellular material (ECM) on outside of
  membrane
• ECM makes a strong cell wall
• Diatoms shells of silica

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Locomotion organelles

• Varies
• Flagella (1 or more)
• Several shorter called cilia
• Pseudopodial (false feet)
• Lobopodia-blunt extensions
• Filopodia-thin branch extensions
• Axopodia-supported by microtubules

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Cyst formation

• Protective covering
• In adverse environments
• Dormant forms

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Nutrition

• Phototrophs (photosynthetic)
• Heterotrophs
• Mixotrophs
• Combine photosynthesis with heterotrophic
  nutrition
• Phagotrophs
• Ingest visible particles of food
• Osomotrophs
• Ingest soluble food

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Reproduction

• Asexually
• Binary fission
• Budding
• Sexual reproduction
• Gamete meiosis
• Spore-producing protists are haploid as adults
• Algae alternate haploid/diploid

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Fig. 28-23
RESULTS
Choanoflagellates
Animals
Unikonta
Fungi
Common ancestor of all eukaryotes
Amoebozoans
Diplomonads
Excavata
Euglenozoans
Alveolates
Chromalveolata
Stramenopiles
DHFR-TS gene fusion
Rhizaria
Rhizarians
Red algae
Green algae
Archaeplastida
Plants
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Categories

• 1. Excavata
• 2. Chromalveolata
• 3. Rhizaria
• 4. Archaeplastida
• 5. Unikonta

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1. Excavata

• Diplomonads
• Parabasalids
• Euglenozoans
• CDC

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Diplomonads

• Giardia lamblia (parasite)
• Flagellate protist
• Mitochondria lacking DNA, ETC or enzymes for
  citric acid cycle
• Anaerobic environment
• Found in water
• Cause diarrhea
• hikers diarrhea

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Parabasalids

• Trichomonads
• Reduced mitochondria
• Anaerobic energy production
• T. vaginalis
• Infects vaginal lining
• Disrupts normal acidity of vagina

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Euglenozoans

• Euglenoids
• Mixotrophs
• Earliest free-living eukaryotes
• Fresh water
• Move by flagellum
• Asexually

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Euglena
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Euglenozoan

• Kinetoplastids
• Single mitochondria
• 2 types of DNA
• Parasites
• Typanosomiasis
• African sleeping disease

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2. Chromalveoletes

• Alevolates
• Dinoflagellates
• Apicomplexans
• Ciliates
• Stramenopiles
• Diatoms
• Golden algae
• Brown algae
• Oomycetes

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Dinoflagellates
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Alveolata

• Common trait
• Alveoli (membrane sac)
• Space below plasma membrane

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Dinoflagellates

• Photosynthetic
• Marine freshwater
• Characteristic shape
• Reinforced by internal plates of cellulose.
• Two flagella sit in perpendicular grooves in the
  armor
• Produce a spinning movement
• red tide produced with large growth

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Apicomplexes

• Spore forming parasites
• Spores pass from host to host
• Apical complexes
• Organelles-one of cell
• Plasmodium causes malaria
• Mosquito to human

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Plasmodium
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Malaria
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Toxoplasma gondi
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Ciliates

• Large numbers of cilia
• Anchored to microtubules below membrane
• 2 nuclei
• Macronucleus for mitosis
• Micronucleus for sexual reproduction

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Paramecium
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Paramecium
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Ciliates
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Paramecium
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Stramenopila

• Diatoms
• Brown algae
• Golden algae
• Oomycetes

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Diatoms

• Unique glasslike walls
• Hydrated silica in an organic matrix.
• Overlap like a shoe box lid.
• Photosynthetic
• Mostly unicellular

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Diatoms
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Brown algae

• Largest algae (kelp)
• Multicellular
• Most are marine
• Found in cooler waters
• Color due to carotenoids
• Alternate between diploid haploid cycles
• Thickens foods (ice cream, pudding)

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Brown algae
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Golden algae (Chrysophyta),

• Named for the yellow brown carotene
• Xanthophyll pigments
• Typically bi-flagellated.
• Many freshwater
• Most are unicellular, some are colonial.
• Poor environment
• Form resistant cysts-viable for decades.

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Golden algae (Chrysophyta),
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Oomycetes

• Cellulose in cell walls
• Mostly diploid
• Flagellated cells
• Caused the potato blight in 1845-47
• Turned potato plants to black slime

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3. Rhizaria

• Amoebas
• Forams
• Radiolarians

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Amoebas

• Pseudopods
• Flowing extension of cytoplasm
• Pulls amoeba forward
• Causes dysentery

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Amoebas
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Forams

• Almost all marine.
• Most live in sand or attach to rocks or algae.
• Some are in plankton.
• Multi-chambered, porous shells
• Consists of organic materials
• Hardened with calcium carbonate
• Tests

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Forams
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Radiolarians

• Marine
• Internal skeleton made of silica
• Skeleton lines seafloor when dies

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Radiolarians
200 µm
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4. Archaeplastida

• Red algae
• Green algae

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Rhodophyta

• Red algae
• Microscopic to large seaweed on beach
• Mostly multi-cellular
• Warm coastal waters
• Used in sushi

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Red algae
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Chlorophyta

• Green algae
• Green chloroplasts
• Similar to plants
• Diverged recently
• Mostly live in fresh water
• Unicellular to multi-cellular

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Green algae
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5. Unikonta

• Slime molds
• Choanoflagellida

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Slime molds

• Looks like a moving mass of slime
• Plasmodium
• A multinucleated mass of cytoplasm
• Move as a mass called a slug
• Digest bacteria, yeasts other small organic
  particles
• Multi-cellular unicellular

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Slim molds
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Slim molds
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Slim molds
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Slim mold
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Choanoflagellida

• Similar to sponges
• Freshwater
• Single flagellum
• Feed on bacteria

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Fig. 28-UN6