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What is this? Why is it
important? Why is this today’s
question?
ProtistsProtists
By Brian Kato, Adam Resnick, and Yukako Kawakatsu
By Brian Kato, Adam Resnick, and Yukako Kawakatsu
IntroductionIntroduction
• Protists are a diverse group of eukaryotes that are not animals, plants or fungi.
• They can be unicellular or multicellular, but do not have any specialized tissues.
• It is hard to come up with a specific definition of a protists owing to their diversity.
• Protists are a diverse group of eukaryotes that are not animals, plants or fungi.
• They can be unicellular or multicellular, but do not have any specialized tissues.
• It is hard to come up with a specific definition of a protists owing to their diversity.
EndosymbiosisEndosymbiosis
• Endosymbiosis is a theory which explains the origins of plastids in eukaryotes.
• It states that chloroplasts and mitochondria evolved from small bacteria engulfed by larger bacteria.
• The small bacteria remained alive within the large ones, and they developed a symbiotic relationship.
• Endosymbiosis is a theory which explains the origins of plastids in eukaryotes.
• It states that chloroplasts and mitochondria evolved from small bacteria engulfed by larger bacteria.
• The small bacteria remained alive within the large ones, and they developed a symbiotic relationship.
Secondary EndosymbiosisSecondary Endosymbiosis
• A larger organism engulfs a smaller one which has already undergone endosymbiosis.
• This explains the diversity of plastids which are found in protists.
• It is more difficult to determine which plastids were acquired through secondary endosymbiosis in organisms which underwent this process in the distant past.
• A larger organism engulfs a smaller one which has already undergone endosymbiosis.
• This explains the diversity of plastids which are found in protists.
• It is more difficult to determine which plastids were acquired through secondary endosymbiosis in organisms which underwent this process in the distant past.
Protozoa• Similarities to Animals: ・Mobility, digestion, ingestion
Algae• Similarities to plants: ・ Chloroplasts (produce own food), thall
us (parts that correlate to plant structure)• Differences: ・ Lack leaves, roots, flowers, and other organ str
uctures.Fungus-like
• Similarities to fungus:• Reproduce by spores• Have hyphae (branch-like structure used to absorb nutrients)• Difference:• Use different materials in their cell walls-protists use cellulos
e, fungi use chitin.• They can behave as amoebas at times, while fungi grow as a
single stationary unit.
Protozoa• Similarities to Animals: ・Mobility, digestion, ingestion
Algae• Similarities to plants: ・ Chloroplasts (produce own food), thall
us (parts that correlate to plant structure)• Differences: ・ Lack leaves, roots, flowers, and other organ str
uctures.Fungus-like
• Similarities to fungus:• Reproduce by spores• Have hyphae (branch-like structure used to absorb nutrients)• Difference:• Use different materials in their cell walls-protists use cellulos
e, fungi use chitin.• They can behave as amoebas at times, while fungi grow as a
single stationary unit.
Diplomonads• Two equal-sized nuclei• Multiple flagella• Ex: Giardia
Parabasalids• Undulating membrane
Similarities:• Modified mitochondria• Lack plastids• Most found in anaerobic
environments
Diplomonads• Two equal-sized nuclei• Multiple flagella• Ex: Giardia
Parabasalids• Undulating membrane
Similarities:• Modified mitochondria• Lack plastids• Most found in anaerobic
environments
EuglenozoansEuglenozoans
• Predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites
• Spiral or crystalline rod inside flagella• Kinetoplastids: have kinetoplast (DNA
in mitochondria)• ex: Trypanosomes-sleeping sickness (“ba
it-and-switch” defense)• Euglenids: have paramylon as storage
molecule. Switch between heterotrophs/ autotrophs according to availability of nutrients and sunlight(eyespot).
• Predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites
• Spiral or crystalline rod inside flagella• Kinetoplastids: have kinetoplast (DNA
in mitochondria)• ex: Trypanosomes-sleeping sickness (“ba
it-and-switch” defense)• Euglenids: have paramylon as storage
molecule. Switch between heterotrophs/ autotrophs according to availability of nutrients and sunlight(eyespot).
AlveolatesAlveolates Alveoli beneath
plasma membrane Dinoflagellates: armor
of cellulose plates Apicomplexans: apical
complex of organelles Ciliates: cilia used in
movement and feeding; macro and micronuclei.
Alveoli beneath plasma membrane
Dinoflagellates: armor of cellulose plates
Apicomplexans: apical complex of organelles
Ciliates: cilia used in movement and feeding; macro and micronuclei.
StramenopilesStramenopiles Hairy and smooth
flagella Oomycetes: hyphae
that absorb nutrients Diatoms: glassy, two-
part wall Golden algae: flagella
attached near one end of cell
Brown algae: all multicellular, some with alternation of generations
Hairy and smooth flagella
Oomycetes: hyphae that absorb nutrients
Diatoms: glassy, two-part wall
Golden algae: flagella attached near one end of cell
Brown algae: all multicellular, some with alternation of generations
Cercozoans and Radiolarians
Cercozoans and Radiolarians
Amoebas with threadlike pseudopodia
Forams: porous shell Radiolarians:
pseudopodia radiating from central body
Amoebas with threadlike pseudopodia
Forams: porous shell Radiolarians:
pseudopodia radiating from central body
AmoebozoansAmoebozoans Amoebas with lobe-shaped
pseudopodia Gymnamoebas: soil-
dwelling, freshwater, or marine
Entamoebas: parasites Plasmodial slime molds:
multinucleate plasmodium; fruiting bodies that function in sexual reproduction.
Cellular slime molds: multicellular aggregate that forms asexual fruiting bodies.
Amoebas with lobe-shaped pseudopodia
Gymnamoebas: soil-dwelling, freshwater, or marine
Entamoebas: parasites Plasmodial slime molds:
multinucleate plasmodium; fruiting bodies that function in sexual reproduction.
Cellular slime molds: multicellular aggregate that forms asexual fruiting bodies.
Red AlgaeRed Algae
Phycoerythrin (accessory pigment) No flagellated stages
Phycoerythrin (accessory pigment) No flagellated stages
Life Cycle of Multicellular Algae (Alternation of Generation)
Life Cycle of Multicellular Algae (Alternation of Generation)
Biological NicheBiological Niche Parasites (ex: malaria, sleeping sickness,
dysentery) Dinoflagellates
Red tide Mutualistic symbionts of coral polyps and the giant clam
Water molds (oomycetes) Potato late blight
Diatoms Diatomaceous earth mined as filtering medium Nanotechnology-microscopic devices
Algae Food (seaweed, soups, used to thicken pudding, ice
cream, salad dressing) Forests house marine creatures Watermelon snow Live symbiotically w/in other eukaryotes-contribute part
of their photosynthetic output to food supply of hosts (lichens)
Parasites (ex: malaria, sleeping sickness, dysentery)
Dinoflagellates Red tide Mutualistic symbionts of coral polyps and the giant clam
Water molds (oomycetes) Potato late blight
Diatoms Diatomaceous earth mined as filtering medium Nanotechnology-microscopic devices
Algae Food (seaweed, soups, used to thicken pudding, ice
cream, salad dressing) Forests house marine creatures Watermelon snow Live symbiotically w/in other eukaryotes-contribute part
of their photosynthetic output to food supply of hosts (lichens)
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