Taxonomy Eukaryotes Part II Flashcards
Stramenopiles
Phylum - All have flagella with many short hair-like extensions
Can be chemoheterotroph or phototrophic
Can contain red algae chloroplasts by endosymbiosis
Examples: oomycetes, diatoms, golden algae, brown algae
Stramenopiles: oomycetes
Chemoheterotrophic
AKA water molds, with filamentous growth and coenocytic hyphae - like fungi but with cellulose walls
Ex. Phytophthora infestans potato famine disease
Stramenopiles: golden algae
Phototrophic
AKA Chrysophytes, golden-brown color
- chloroplast pigments dominated by carotenoid fucoxanthin
Unicellular mostly, some colonies
Stramenopiles: diatoms
Unicellular phototrophs, 100,000 species
- 200 million years old
Found in freshwater and marine habitats
Frustules: cell walls made of silica with proteins + polysaccharides for protection
Cercozoans and Radiolarians general
Cercozoans
Radiolarians
Protists with threadlike pseudopodia
- Unicellular and quite small
Cercozoans: marine organisms
- form shell-like structures called Tests
- tests made from organic materials reinforced with calcium carbonate
Radiolarians: mostly marine, heterotrophs
- Tests radially symmetric and made of silica
Amoebozoa
Types: Gymnoamoebas, Entamoebas, Slime molds
Terrestrial and aquatic protists that use pseudopodia for movement and feeding
- phagocytosis of bacteria/protists
- cytoplasmic streaming - movement
Includes:
Gymnoamoebas: free-living, in soil, and aquatic environs
Entamoebas: GI parasites of vertebrates and invertebrates
Slime molds:
- motile (actin)
- similar life cycle to fungi with fruiting bodies producing spores
Plasmodial slime mold life cycle
Genus Physarum
Vegetative form: masses of protoplasm that contain multiple nuclei (plasmodium)
Sporangium forms from plasmodium containing haploid spores (dormant, resistant)
Spores germinates forming swarmer cell
- can be flagellated or amoeboid
Fusion of 2 swarmers forms diploid plasmodium again
Cellular slime mold
Species Dictyostelium discoideum
Vegetative form: single haploid amoebae
Aggregation of amoebae β> pseudoplasmodium to move as single unit
- but cells donβt fuse
Fruiting body forms β> differentiation into spores
- or may form diploid macrocysts to undergo meiosis β> new haploid amboeba for sexual reproduction
Base definition of fungi
Conidia
Feeding mechanism
Multicellular, forming a network of mycelium hyphae
- Coenocytic - no division between cells
- septate - nuclei separated by cross walls
Cell walls made of chitin
Conidia = asexual spores produced by hyphae that extend above the surface
- pigmented and resistant to drying
Feeding mechanism: release of extracellular enzymes to digest complex organic material from polymers into monomers for reassembly
Symbiosis and pathogenesis of fungi and types of relationships
Symbiotic: mycorrhizae symbiosis with plant roots - help plant roots obtain phosphorus and fungi gets nutrients from plants
Ectomycorrhizae: sheath around root but no penetration
Endomycorrhizae: fungal hyphae embedded in plant roots
Haustoria: specialized hyphae which penetrate plant or animal cells and consume cytoplasm (pathogenic)
Mycoses: fungal infection in animals range in severity
- immunosuppression is a risk factor
Asexual reproduction of fungi
1) growth and spread of hyphal filaments
2) asexual production of spores
3) cell division (budding)
- scars can be seen from this
4) sexual production of spores:
- originate from fusion of 2 haploid cells β> meiosis β> haploid spores
- spores: ascospores, basidospores, zygospores
- resistant to drying, heating, freezing and chemicals
Cell cycle of Saccharomyces cerevisiae
Cell division through budding, and sexual reproduction through mating types a and π
1) Diploid cell undergoes meiosis β> ascospores (haploid)
2) Germination of ascospores β> a and π types
3) Asexual reproduction (mitosis) of a/π types
4) Mating of a + π types by cell fusion β> 2 nuclei cell β> nuclear fusion to form diploid cell
5) Diploid cells can proliferate by asexual reproduction (mitosis)
