Biology of eukaryotic microorganisms Single or multicellular

1. 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

2. Eukaryotes may reproduce sexually And asexually!

3. 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

4. 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

5. 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

6. Major groups of algae

7. 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

8. 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?

9. A multicellular alga • Note the similarities to plant structures • Specialized for photosynthesis and maintaining position

10. 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

11. 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

12. Protozoans Single- celled Not photosynthetic Usually motile Traditionally grouped according to means of locomotion Classified as Protista (so far)

13. Major categories of pathogenic protozoa

14. Sarcomastigophora subphylum Mastogiphora (flagellated) important pathogenic genera: Trypanosoma, Giardia, Leishmanii, among others subphylum Sarcodina (pseudopodia) Entamoeba histolytica

15. 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

16. 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)

17. Giardia

18. Asexual reproduction in protozoans

19. 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

20. 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)

21. 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

22. All have chitin; none are ever flagellated

23. 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?

24. Yeasts reproduce by fission or budding

25. Molds form hyphae Some fungi are dimorphic- molds in the soil, yeasts in the body

26. 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

27. Lichens: a symbiotic relationship

28. Commercial importance of fungi Fermentation Basic research Biotechnology

29. Slime molds and water molds • Terrestrial- plasmodial or cellular • Acts as detrivores or consumers • Oomycetes (water molds) major plant pathogens

30. Multicellular parasites helminths (worms) nematodes (roundworms) trematodes (flukes) cestodes (tapeworms) arthropods insects, ticks, fleas, lice, mites mechanical vectors biological vectors

31. Mosquitoes are important disease vectors • Designed to bite and suck blood from host • Different species transmit different diseases

32. 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)

33. Add dengue to the list…

34. 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

35. Life cycles can be complex Primary and secondary hosts

37. General strategies for controlling parasitic diseases Vector control Medication Vaccination Genetic engineering?

38. 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