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Protists & Fungi Lecture #6. Protists Protozoa – animal-like unicellular, usually motile –lack cell wall chemoorganoheterotrophs __________ –study of.

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Presentation on theme: "Protists & Fungi Lecture #6. Protists Protozoa – animal-like unicellular, usually motile –lack cell wall chemoorganoheterotrophs __________ –study of."— Presentation transcript:

1 Protists & Fungi Lecture #6

2 Protists

3 Protozoa – animal-like unicellular, usually motile –lack cell wall chemoorganoheterotrophs __________ –study of protozoa

4 Protists 1.Protists considered to be the first eukaryotes to appear on Earth 2.__________ organisms, but some exist as colonies of cells – colonial organisms 3.Asexual reproduction by mitosis is most common 4.Major evolutionary advance: development of eukaryotic cellular features such as __________, mitochondria, chloroplasts and other organelles

5 Protozoa Lack cell walls Ingest food particles Move about freely Produce no sporebearing structures Active feeding form: trophozoites, transform into protective bodies (cysts) under harsh conditions Part of the zooplankton, the animal-like component of aquatic food chains Classified by types of motion

6 Distribution primarily in moist habitats most are free-living in aquatic environments terrestrial protozoa usually found in decaying organic matter and soil some parasitic in plants and animals

7 Importance important link in food chains and food webs –food chains – series of organisms, each feeding on the preceding one –food web – complex interlocking series of food chains –make up large part of plankton in aquatic habitats research –model organisms because have same metabolic pathways as multicellular eucaryotes causative agents of some important diseases in humans and other animals

8 Four Major Groups of Protozoa

9 Amoebas Move by __________ Heterotrophs Reproduction primarily through mitosis Evidence for sexual reproduction in certain species Some have shell-like casings (foraminifera have calcium carbonate shells and heliozoa and radiolaria have silicon dioxide shells)

10 Foraminifera and Radiolaria radiolaria foraminifera

11 Flagellates All flagellates have __________ May be regarded as the most fundamental protists Euglena: autotrophic in sunlight (chloroplasts) and heterotrophic in dark Trichonympha: breakdown cellulose in termite hindgut

12 Flagellates Volvox: colonial organisms, some in colony specialize in feeding others reproduction. Giardia lamblia: causes diarrhea when ingested (contaminated waters )

13 Endosymbiosis Hypothesis

14 Ciliates Diverse group of heterotrophic protozoa Sizes range from 10  m to 3 mm Movement of __________ is coordinated by a primitive nerve network running beneath the surface of the cell Have 2 types of nuclei (macronucleus and micronuclei) Not all ciliates are motile Paramecium

15 Forming Cysts formation and germination of cysts formation of a cyst –resting state with a wall and low metabolic activity –function of cysts protection from changes in environment transfer from one host to another escape of vegetative form from cyst usually triggered by return to favorable environment __________ –vegetative form released by parasitic species –excystation often triggered by entry into new host

16 Reproduction asexual –usually by binary fission mitosis followed by cytokinesis sexual –usually by conjugation exchange of gametic nuclei between paired protozoa of opposite mating types

17 Sporozoa At some stage in life cycle  develop a sporelike body Virtually all sporozoa are parasitic Toxoplasma gondii, causative agent for toxoplasmosis Cryptosporidium, intestinal illness

18 Important sporozoan genera Plasmodium – __________ Cryptosporidium – cryptosporidiosis Toxoplasma – toxoplasmosis Eimeria - coccidiosis

19 Unicellular Algae Unicellular algae – phytoplankton in the oceans Generate most of the atmospheric oxygen Produce half of the Earth’s organic matter Six divisions (3 – unicellular and 1 – unicellular and multicellular) Pyrophyta Chrysophyta Euclenophyta Chlorophyta

20 Algae eucaryotes that have chlorophyll and other pigments for carrying out oxygenic photosynthesis lack well-organized vascular conducting system have simple reproductive structures __________ –study of algae

21 Distribution of Algae primarily aquatic –planktonic suspended in aqueous environment phytoplankton –algae and small aquatic plants zooplankton –animals and nonphotosynthetic protists –benthic attached and living on the bottom of a body of water –neustonic live at water-atmosphere interface

22 Distribution… some terrestrial –on moist surfaces –endosymbionts in protozoa, mollusks, worms, and corals –associate with fungi to form lichens

23 Algal Nutrition can be either autotrophic or heterotrophic –most are photoautotrophic –some are chemoorganoheterotrophic

24 unicellular motile colonial filamentous membranous and blade- like tubular

25 Phyrophyta: Dinoflagellates Fire-algae: bright red and orange pigments Red tides – can be toxic Bioluminescent

26 Chrystophyta: Diatoms Golden-brown and yellow-green algae Silicon dioxide shells

27 Diatomaceous earth deposits of empty diatom shells has numerous uses –cleaning and polishing agents –deodorizers –fertilizers –filters –soundproofing and insulating materials –paint additive increase night visibility of license plates and signs

28 Euglenophyta Earlier under flagellates: animallike and plantlike Euglena: autotrophic in sunlight (chloroplasts) and heterotrophic in dark

29 Chlorophyta Include both unicellular and multicellular algae Chlamydomonas and Volvox as examples Chlamydomonas Volvox: also from flagellates

30 Slime Molds and Water Molds Slime Molds Resemble plants – enclosed in cell wall made of cellulose Resemble animals – during life cycle have flagellated cells Water Molds Live in water and damp soil Phytophthora infestans (late blight of the potatoes, responsible for the deaths of millions of Irish people in 1847)

31 Fungi

32 Decomposers of organic matter Most fungi composed of threadlike strands called hyphae that collectively form a interwoven mass called a mycelium Have nuclei Most species form spores Non motile Most are heterotrophic Reproduce by both sexual and asexual means Cell walls contain chitin, a polysaccharide not found in plants Two types: __________(single-celled) __________(filamentous)

33 True fungi fungus (pl., fungi) –eucaryotic –spore-bearing –chemoorganoheterotrophs with absorptive metabolism –reproduce sexually and asexually –belong to kingdom Fungi (Eumycota) within domain Eucarya

34 Some terms __________ –study of fungi mycologists –scientists who study fungi mycotoxicology –study of fungal toxins and their effects mycoses –diseases caused by fungi

35 Distribution primarily terrestrial –few aquatic species many are pathogenic in plants or animals some form associations –mycorrhizae – associations with plant roots –lichens – associations with algae or cyanobacteria

36 Importance beneficial impact –decomposers –industrial fermentations fermented foods and beverages steroids, antibiotics and other drugs –research model eucaryotic organisms detrimental impact –major cause of plant diseases –cause of many animal, including human, diseases

37 Fungi Four divisions Zygomycota – form sexually produced zygospores [Ex. Rhizopus black bread mold] Ascomycota – sexually produced ascospores form within a saclike ascus (tiny spore containing sac) [Ex. Penicillium] Basidiomycota – sexually produced basidiospores form on a supportive structure called a basidium [Ex. mushrooms] Deuteromycota – sexual cycle of reproduction unknown


39 Yeasts Reproduce asexually by __________(new cell grows and pinches off) or reproduce sexually by formation of spores Saccharomyces species used in bread baking and making alcohol

40 Molds filamentous fungi –hyphae (s., hypha) the __________ of a mold may be coenocytic (no cross walls) or have septa (cross walls) –mycelium (pl. mycelia) bundles or tangled masses of __________

41 Lichens Lichens are organisms resulting from associations between a fungus and a photosynthetic partner (cyano or unicellular alga) __________ : photosynthetic partner makes sugar and carbohydrates while fungal partner provide protection from harsh environment and provides nutrients.

42 Mycorrhizae Mutualistic association between fungi and plants Roots of 80% of vascular plants are belived to have these fungi Fungal cells provide nutrients (particularly phosphorus) and water while the plant supplies products of photosynthesis

43 Fungi and Disease Yeast infections: Candida albicans Other disease causing fungi: Athlete’s foot Ringworm


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