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Biology of eukaryotic microorganisms Single or multicellular Photosynthetic (autotrophic) or heterotrophic Classification is now based on ribosomal RNA or other molecular structures algae protozoans fungi helminths and arthropods. Eukaryotes may reproduce sexually. And asexually!.
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Biology of eukaryotic microorganisms Single or multicellular Photosynthetic (autotrophic) or heterotrophic Classification is now based on ribosomal RNA or other molecular structures algae protozoans fungi helminths and arthropods
Eukaryotes may reproduce sexually And asexually!
Classification of eukaryotes • Organisms that look alike may be very different from each other • Arose at different times in Earth’s history • This chart highlights algae
Algae not actually that closely related to each other but have features in common Photosynthetic (chlorophyll a and other pigments) Can be unicellular or multicellular No vascular system Reproduce by mitosis or formation of flagellated gametes
Algae live in both fresh and salt water Unicellular: phytoplankton food source oxygen source Can live nearly anywhere Multicellular: kelps, read and green algae Major “producer” in ecosystems
Examples of algae: macroscopic and microscopic • Volvox: freshwater; form colonies • Corallina (red algae): saltwater • Different pigments enable them to live at different depths of water • Agar and carrageenan harvested from red algae
Diatoms have unique silica shells • “diatomaceous earth” is formed from the shells of dead diatoms • Oil deposits were formed from diatoms • Can we “grow” oil in diatoms today?
A multicellular alga • Note the similarities to plant structures • Specialized for photosynthesis and maintaining position
Algal toxins • Dinoflagellates are chief sources (red tides) • Gymnodinium breve- brevetoxin • Gonyaulax- saxitoxin and gonyautoxins • Pfisteria spp.- toxin or parasite? • People get sick by eating contaminated fish and seafood
SUMMARY OF ALGAE Algae classified according to: photosynthetic pigments storage molecules (starch, fats, oils) fresh or salt water Some are motile, at least at some point in their life cycle Some produce toxins
Protozoans Single- celled Not photosynthetic Usually motile Traditionally grouped according to means of locomotion Classified as Protista (so far)
Sarcomastigophora subphylum Mastogiphora (flagellated) important pathogenic genera: Trypanosoma, Giardia, Leishmanii, among others subphylum Sarcodina (pseudopodia) Entamoeba histolytica
Cilipohora- move by cilia (or obtain food that way) most are free-living Balantidium coli causes GI disease Apicomplexa- obligate parasites Plasmodium, Toxoplasma, Cryptosporidia others parasitize other hosts Many other phyla found in the natural world, but not implicated in human disease
Protozoans can have complicated life cycles trophozoites (feeding stage) various intermediate stages cysts (resistant stages) Reproductive activity can vary too Asexual fission budding schizogony (multiple fission)
Sexual meiosis to produce gametes syngamy- gametes from different individuals autogamy- gametes are formed and then fuse conjugation- gametes are formed and exchanged between pairs of organisms
Habitats of protozoa • Everywhere- but they do need water • Most are free-living • Part of food chain and energy cycling • Decomposers (detrivores) • Parasites • Symbiosis (guts of ruminants)
Fungi are NOT photosynthetic: “saprophytes” Important plant pathogens; animals generally less susceptible to fungal infection (if their immune systems are working well) Fungi are classified traditionally by means of sexual reproduction Molecular analysis can lead to reclassification
Fungi vary widely in size and locales • World’s largest mushroom in Oregon (approx. 4 sq. mi.) • (or is it China? Alberta?) • May be over 7,000 years old • Largest living thing?
Molds form hyphae Some fungi are dimorphic- molds in the soil, yeasts in the body
Fungi can grow almost anywhere and under a wide variety of conditions Often form symbiotic relationships with other organisms Can have harmful effects, too allergens mycoses toxins food spoilage
Commercial importance of fungi Fermentation Basic research Biotechnology
Slime molds and water molds • Terrestrial- plasmodial or cellular • Acts as detrivores or consumers • Oomycetes (water molds) major plant pathogens
Multicellular parasites helminths (worms) nematodes (roundworms) trematodes (flukes) cestodes (tapeworms) arthropods insects, ticks, fleas, lice, mites mechanical vectors biological vectors
Mosquitoes are important disease vectors • Designed to bite and suck blood from host • Different species transmit different diseases
Additional biting insects and arachnids (and diseases) • Ticks (Lyme disease, Rocky Mountain spotted fever) • Lice (typhus, trench fever, itchy reactions) • Fleas (bubonic plague, tapeworm) • Mites (scabies, other itchy rashes), scrub typhus)
Helminths- it’s Greek for worm • Nematodes- roundworms • Male and female (separate sexes) • Some free-living, some parasitic • Have complete digestive tracts • Cestodes-tapeworms (flatworms) • Hermaphroditic • Absorb nutrients- no digestive system • Trematodes-flukes • Also hermaphroditic (“monoecious”) • Many have complicated life cycles with multiple hosts
Life cycles can be complex Primary and secondary hosts
General strategies for controlling parasitic diseases Vector control Medication Vaccination Genetic engineering?
Summary • Eukaryotic microbes play essential roles in the environment • Adapted to diverse environments • Historically classified by appearance and how they obtain (or make) food, reproduce, etc. • Some cause serious disease