Kingdom PROTISTA: What are protists?
Domain Eukarya Eukaryotes have a Nucleus and many organelles! Defined by exclusion –
Cannot be classified as plants, animals or fungi Diverse in body, obtaining food, and movement
How did eukaryotes evolve?
Probably evolved 2 billion years ago Arose through endosymbiosis
One organism lives inside another organism Photosynthetic prokaryote lived inside another
prokaryote chloroplast Aerobic prokaryote lived inside another
prokaryote mitochondrion cDNA and mDNA is similar to Bacteria DNA
How did eukaryotes evolve?
PROTISTA characteristics: body plans
Most are unicellular (example, Paramecium) Some small multicellular colonies (example, Volvox) Some large multicellular colonies (example, kelp)
paramecium volvox kelp
PROTISTA characteristics: obtaining food
Some protists are autotrophs Absorb energy of sun through pigments Make their own food through photosynthesis
light energy + 6H20 + 6CO2 C6 H1206 + 6O2
PROTISTA characteristics: obtaining food
Other protists are heterotrophs Get their food by eating other organisms Release energy by cellular respiration
C6 H1206 + 6O2 6H20 + 6CO2 + energy(ATP)
PROTISTA characteristics: motility
Some move with long, whip-like flagella Others move with shorter cilia Others move by extended pseudopodia
flagella
cilia
pseudopodia
PROTISTA asexual reproduction
Most protists reproduce asexually Binary fission 1 cell divides into 2 equal size cells Multiple fission 1 cell divides into more than 2
How do the offspring compare? Offspring are genetically identical to parent Similarity is created by the process of mitosis
PROTISTA sexual reproduction
Some protists can reproduce sexually Protist conjugation 2 cells join, exchange DNA
How do the offspring compare? Resulting offspring are genetically unique Uniqueness is created by the process of meiosis
Animal-like PROTISTA
Move like animals Heterotrophic: obtain food like animals NOT closely evolutionarily linked to animals
Animal-like PROTISTAPhylum Protozoa
Body plan: unicellular Motility: form pseudopodia
Heterotrophic: absorb food by endocytosis
pseudopod
Animal-like PROTISTAPhylum Protozoa
Animal-like PROTISTAPhylum Ciliophora
Body plan: unicellular
Motility: cilia beat in waves Heterotrophic: cilia sweep food into mouth
cilia
Animal-like PROTISTAPhylum Sarcomastigophora
Body plan: unicellular Motility: one or more flagella
Heterotrophic or parasitic Some cause disease
Trypanosoma causes sleeping sickness Giardia contaminates water
Fly takes up blood and injects trypanosomes
Trypanosomes enter bloodstream
Trypanosomes reproduce by mitosis in blood and spinal fluid
Trypanosomes spread in circulatory and nervous systems
Fly takes up blood and trypanosomes
In fly gut, trypanosomes transform → promastigotes and reproduce by mitosis
Promastigotes leave the fly gut and transform → epimastigotes
Epimastigotes reproduce by mitosis in the salivary gland and transform → trypanosomes
Animal-like PROTISTAPhylum Apicomplexa
Body plan: unicellular Motility: no means of locomotion
All are parasitic Some cause disease
Plasmodium causes malaria Cryptosporidium contaminates water
Mosquito takes up blood and injects sporozoites
Sporozoites invade liver cells
Sporozoites transform → schizonts
Schizonts transform → merozoites.Liver cells rupture
Merozoites invade blood cells
Asexual route: merozoites → schizonts → merozoites → blood cells rupture
Sexual route: some merozoites transform → gametocytes
Mosquito takes in ♂ and ♀ gametocytes
In mosquito stomach, ♂ gamete penetrates ♀ gamete → zygote
Zygote transforms → ookinete
Ookinete invades mosquito gut, transforms → oocyst
Oocysts grow, rupture, release sporozoites
Fungus-like PROTISTA
Often called molds but NOT in Kingdom Fungi Protist cell walls are composed of cellulose Fungi cell walls are composed of chitin
Fungus-like PROTISTAPhylum Myxomycota (plasmodial slime molds)
Body plan: unicellular or multicellular Mobile and stationary life stages
Fungus-like PROTISTAPhylum Myxomycota (plasmodial slime molds)
Mobile stage of life cycle Forms plasmodium: mass of cytoplasm Creeps by amoeboid-like streaming Consumes decaying plants by endocytosis
Fungus-like PROTISTAPhylum Myxomycota (plasmodial slime molds)
Stationary stage of life cycle Reproduces when food is scarce Forms sporophores: spore-bearing structures
Fungus-like PROTISTAPhylum Oomycota (water molds)
Body plan: unicellular and multicellular Motility: flagella
Parasitize fish and many crop plants
Plant-like PROTISTA
Autotrophic: obtain food like plants Lack true roots, stems, and leaves
Plant-like PROTISTAFour basic body plans
1 unicellular known as phytoplankton
2 colonial coordinated group of cells
3 filamentous slender, stringy
4 multicellular often large and complex
Plant-like PROTISTATypes of pigments
chlorophyll phycobilin
fucoxanthin carotenoid
Chlorophyll absorbs red and blue light
Other pigments absorb other wavelengths
√ Efficient photosynthesis
PigmentsChlorophyll – green
Phycobilin – blue-green, yellow, and red
Fucoxanthin – brown and olive-green
Carotenoid – red, orange, and yellow
Plant-like PROTISTAPhylum Chlorophyta (green algae)
Diverse body forms: all four
Diverse habitats: aquatic, moist terrestrial, symbiotic relationships
Pigments: chlorophyll and carotenoids Share common ancestor with plants?
(same pigments and cell wall composition)
Plant-like PROTISTAPhylum Phaeophyta (brown algae)
Body form: multicellular Pigments: chlorophyll and fucoxanthin Habitat: cold, nutrient-rich, rocky coasts
Some of the largest algae known
Plant-like PROTISTAPhylum Rhodophyta (red algae)
Body form: multicellular Pigments: chlorophyll and phycobilin Phycobilin can absorb deep-penetrating light
Rhodophyta can live at great depths
Plant-like PROTISTAPhylum Bacillariophyta (diatoms)
Body form: unicellular or colonial Pigments: chlorophyll, carotenoids, fucoxanthin 2-piece shells have radial or bilateral symmetry
Important role as producers in food web
Plant-like PROTISTAPhylum Dinoflagelleta (dinoflagellates)
Body form: unicellular Pigments: chlorophyll and carotenoids
Some species produce a red tide Turn water reddish during population explosion Red tide toxin can kill large numbers of fish
Plant-like PROTISTAPhylum Chrysophyta (golden algae)
Body form: unicellular and colonial Pigments: chlorophyll, carotenoids, fucoxanthin Resistant cysts allow survival beneath frozen lakes
in winter and dry lakes in summer
Store surplus energy as oil
Plant-like PROTISTAPhylum Euglenophyta (euglenoids)
Body form: unicellular Pigments: chlorophyll, carotenoids
Autotrophic (photosynthetic) and heterotrophic (eyespot and flagellum)