ECOL 182R 1st Edition Lecture 8 Outline of Last Lecture I Protists are a paraphyletic group II Importance of protists III Morphological features IV Feeding V Movement VI Sex VII Key lineages Outline of Current Lecture I Protist families II Fungi A Ecological roles B Diseases C Structure Current Lecture Families of protists Diplomonadida Each cell has 2 nuclei each associated with four flagella Very deep branching early eukaryote Backpacker s diarrhea Euglenida Freshwater marine Roughly 30 do photosynthesis all feed by ingestion Full of chloroplasts It s hybrid it can get energy from chloroplasts but in the dark it can also hunt down little organisms Ciliata Fresh salt water wet soils Covered with cilia Micro and macronucleus Micronucleus impact full length chromosomes copies are made then moved to the macronucleus Macronucleus where the action takes place Dinoflagellata Marine freshwater roughly 50 are photosynthetic Two sets of flagella Show some bioluminescence when they re agitated they send of a spark of light Cause of red tides Diatoms Silicon rich shell Photosynthetic Most important producer of carbon compounds in fresh saltwater Big fossil record on these guys Brown Algae The only multicellular of all these families 100 foot protist Includes most kelps Foraminifera Foramen hole for the holes in the test through which pseudopodia emerge Extensive record in the fossil record Amoeboza Amoeba slime molds Originally thought to be very primitive distant common ancestors with animals The molecular data shows that they have a more recent common ancestor to animals than they do to plants FUNGI Terrestrial ecosystems Feed by absorption Unusual life cycles Ecological roles Critical in soil plant interactions Mycorrhizal fungi Primary decomposers in land ecosystems Saprophytes are fungi that make their living by digesting dead plants Critical agents in land carbon cycle Only eukaryote that can fully digest wood Hypothesis the thick coal deposits laid down during carboniferous period happened cause the swamps had too low a Ph for fungi hence the wood didn t decompose Some can cause diseases Plant diseases rusts smuts mildews blights major impact on some crops A few human diseases valley fever athlete s foot vaginitis ringworm Fungi either exist as single cells yeast or complex filaments mycelia Structures in the mycelia Hyphae individual filaments Heterokaryon most hyphae are haploid Within a hyphae for many species there can be two distinct haploid nuclei Septa No true cell walls within the hyphae which have septa holes Hence the mycelia is somewhere between a multicellular a giant single celled organism Because mycelia are made of hyphae fungi have a very high surface area to volume ratios Makes absorption extremely efficient but also makes fungi prone to drying out Fungi do extracellular digestion Fungi have unusual life cycles with sex occurring with mycelia or yeast of different mating types fusing Fungal Life Cycles Fertilization happens in 2 steps 1 Fusion of cells 2 Fusion of nuclei from the fused cells These 2 steps can be separated in both time space Plasmogamy occurs when the cytoplasms fuse If the nuclei remain independent the mycelium becomes heterokaryotic Karyogamy occurs when the nuclei fuse Fungal reproductive structures Don t have sexes but mating types a and alpha can mate but not a with a nor alpha with alpha Gametes spores with flagella Zygosporangium Hyphae of different mating types yoked together Basidia spores formed on little pedestals Asci spores formed in sacs Reproductive structures used to classify fungi Chytridiomycota only fungi with mobile cells as they produce spores gametes with flagella Zygomycota have zygosporangium yoke structure Basidiomycota basidia form at the ends of hyphae produce spores Ascomycota Tips of hyphae produce distinctive saclike cells called asci that generate spores Macrosporidia All microsporidia are single celled and parasitic with a polar tube that allows them to enter the interior of the cells they parasitize Have a dramatically reduced genome and lack functioning mitochondria Chytridiomycota Largely aquatic especially freshwater Produce motile cells Most chytrid species produce spores that swim to new habitats via a flagellum
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