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What is this? Why is it

important? Why is this today’s

question?

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.

PhylogenyPhylogeny

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

Chlorophya (green algae)Chlorophya (green algae)

Plant-type chloroplasts Plant-type chloroplasts

Ciliate Life CycleCiliate Life Cycle

Plasmodium Life CyclePlasmodium Life Cycle

The Life Cycle of a Water Mold

The Life Cycle of a Water Mold

Life Cycle of Multicellular Algae (Alternation of Generation)

Life Cycle of Multicellular Algae (Alternation of Generation)

Life Cycle of Plasmodial Slime Mold

Life Cycle of Plasmodial Slime Mold

Life Cycle of Cellular Slime Mold

Life Cycle of Cellular Slime Mold

Life Cycle of Unicellular Chlorophyte

Life Cycle of Unicellular Chlorophyte

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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