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o Include any eukaryote not a plant, animal, or fungus
- o Mostly single-celled
- o Approximately 60,000 species
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o Include any eukaryote not a plant, animal, or fungus
- o Mostly single-celled
- o Approximately 60,000 species
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autotrophs
Photosynthetic protists are collectively known as algae
Ingest food with pseudopod
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heterotrophs
Absorb nutrients from surroundings
Single-celled, non-photosynthetic protists are collectively known as protozoa
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o Reproduce asexually by mitosis
- o Some also reproduce sexually
- o Occurs during certain time of year or circumstances (e.g. a crowded environment or a food shortage)
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o Lack mitochondria
- o 2 major groups
- - Diplomonads: have two nuclei and move about by means of multiple flagella
- - Parabasalids: live inside animals
- o Diplomonads
- -Giardia: a parasitic diplomonad
- -Acquired by hikers who drink from infected streams, diarrhea and nausea
- -Cyst phase released in animal feces
- +develop into adult form after ingestion
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o Have distinctive mitochondria
- o 2 major groups
- Euglenids
- Kinetoplastids
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Single-celled, fresh-water protists
- Best known example is Euglena
- Moves by whipping single flagellum
- Photosynthetic
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All species have one or more flagella
- Can be used for propulsion or food gathering
- Trypanosomes infect the blood causing African sleeping sickness
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o Have fine, hair-like projections on flagella
- o Some are photosynthetic
- o Major stramenophile groups
- Water molds
- Diatoms
- Brown algae
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Also known as oomycetes
- Long filaments aggregated into cottony tufts
- Many are soil and water-based decomposers
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Found in both fresh and salt water
- Part of floating phytoplankton community
- Perform 70% of all photosynthesis
- Produce shells of silica
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Form multicellular aggregates (seaweeds)
- Not closely related to plants
- Contain brownish-yellow and green (chlorophyll) pigments
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o Single-celled with small cavities beneath cell surface (alveoli)
- o Photosynthetic, parasitic, and predatory
- o Major alveolate groups
- Dinoflagellates
- Apicomplexans
- Ciliates
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Mostly photosynthetic
- 2 whip-like flagella
- Most species live in salt water
- Nutrient-rich water causes population explosion called "red tides"
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Parasitic
- Form infectious spores
- Spores transmitted between hosts by food, water, or insect bites
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Inhabits both fresh and salt water
- Highly complex unicellular organization
- Paramecium has vacuoles and cilia
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o Have thin, threadlike psuedopods, which extend through hard shells in some species
- o Cercozoans include
- Foraminifera
- Radiolarians
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o Amoebozoans move by extending pseudopods, also used for feeding
- o Aquatic and terrestrial environments
- o Generally do not have shells
- o Major groups of amoebozoans
- Amoebas
- Slime molds
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Found in freshwater lakes and ponds
- Predators that stalk and engulf prey
- One species causes amoebic dysentery
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Distinctly unique lineage among protists
Physical form blurs distinction between a colony versus an individual
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o Multicellular, photosynthetic seaweeds
- o Pigments combined with chlorophyll produce bright red to black appearances
- o Found exclusively in marine environments
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o Photosynthetic
- o Both multicellular and unicellular species
- o Found in both freshwater and marine environments
- o Some form colonies of clustered cells (e.g. Volvox)
- o Mostly microscopic forms but Ulva (sea lettuce) is a multicellular leaf-sized green algal seaweed
- o Green algae are closely related to plants
- o Early plants may have been similar to today’s multicellular green algae
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o Most fungi are multicellular
- o Cells are surrounded by cell walls composed of chitin, a nitrogen-containing polysaccharide
- o Approximately 60,000 species
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o Body of almost all fungi is a mycelium, an interwoven mass of threadlike filaments called hyphae (singular, hypha)
- o Fungal Body Structure
- o Hyphae of most species are divided into many cells by partitions called septa (singular, septum); each cell possesses one or more nuclei
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Nutrition and Fungal Lifestyles
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o All are heterotrophic
- o Secrete enzymes outside their bodies and absorb the digested nutrients
- o Decomposers (saprobes) feed on dead organic material and wastes
- o Parasites absorb nutrients from cells of living hosts
- o Symbiotic fungi live in mutually beneficial relationships
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o Both asexual and sexual reproduction involve the production of spores within fruiting bodies
- o Reproduction
- Asexual occurs under stable conditions
- Fragmentation of the mycelium
- Asexual spore formation by mitosis
- Sexual occurs under unstable conditions
- Hyphae of different fungi fuse
- Haploid nuclei fuse to form a diploid zygote
- Zygote undergoes meiosis to form haploid sexual spores
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o Classified based upon spore production
- Chytridiomycota (chytrids)
- Zygomycota (zygote fungi)
- Ascomycota (sac fungi)
- Basidiomycota (club fungi)
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o Mostly aquatic
- o Reproduce both asexually and sexually
- o Form flagellated spores that require water for dispersal
- o Feed on dead aquatic material
- o Some species are parasites of plants and animals
- One species believed to be a major cause of the worldwide die-off of frogs
- o Primitive chytrids are believed to have given rise to the other groups of modern fungi
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o Most live in soil or on decaying plant or animal material
- o Reproduce both asexually and sexually
- o Sexual spores are thick-walled zygospores
- o Asexual reproduction:
- Haploid spores are produced via mitosis in black spore cases called sporangia
- o Sexual reproduction
- Nuclei fuse to form a diploid zygospore
- o Rhizopus, the black bread mold
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o Live in a variety of marine, freshwater, and terrestrial habitats
- o Reproduce both asexually and sexually
- o Sexual spores form in saclike asci
- o Better known examples include
- Most of the food-spoiling molds, Morels and truffles (edible delicacies), Penicillium, the mold that produces penicillin (the first antibiotic), Yeasts (single-celled fungi)
- o During asexual reproduction
- Haploid spores are produced via mitosis at the tips of specialized hyphae
- o During sexual reproduction
- Each fruiting body contains numerous saclike cases called asci (singular, ascus)
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Basidiomycetes
- o Live in a variety of marine, freshwater, and terrestrial habitats
- o Usually reproduce sexually
- o Sexual spores form in club-shaped basidia
- o Better known examples include
- Mushrooms (some are edible, others are poisonous), Puffballs, Shelf fungi (decomposers of wood), Stinkhorns, Rusts and smuts (plant parasites), Yeasts
- During sexual reproduction:
- o Each fruiting body contains club-shaped structures called basidia (singular, basidium
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o Lichens are symbiotic associations between fungi (usually an ascomycete) and algae or cyanobacteria
- Fungus provides photosynthetic partner with shelter and protection
- Photosynthetic partner provides fungus with food (sugar)
- o Mycorrhizae (singular, mycorrhiza) are symbiotic associations between fungi and plant roots
- Fungus provides plant with water, minerals, and organic nutrients it absorbs from the soil
- Plant provides fungus with food (sugar)
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