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Eukaryotes

Eukaryotes. Protista. What do Eukaryotes have that Prokaryotes do not?. Membrane-bound nucleus Mitochondria, chloroplasts, and endomembrane system Cytoskeleton Flagella of microtubule construction Multiple chromosomes of linear DNA compactly arranged with proteins Diploid life stages

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Eukaryotes

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  1. Eukaryotes Protista

  2. What do Eukaryotes have that Prokaryotes do not? • Membrane-bound nucleus • Mitochondria, chloroplasts, and endomembrane system • Cytoskeleton • Flagella of microtubule construction • Multiple chromosomes of linear DNA compactly arranged with proteins • Diploid life stages • Mitosis and Meiosis and Sex

  3. Compartmentalization of functionsoccurs in eukaryotes

  4. Endosymbiotic theory of eukaryotic evolution • Evidence of mitochondria and chloroplast origin • Appropriate size • Replication by binary fission • Inner membranes containing enzymes and transport systems similar to prokaryotic plasma membranes • DNA is circular and not complexed with histones • Have their own ribosomes, tRNAs and other components for transcription/translation • Ribosomes are more similar to prok. than euk.

  5. A model of the origin of eukaryotes

  6. Protistan taxonomy is in a state of flux (a mess) Your Lab book and your text book approach protists in very different manners using different terminology. Your lab book is the more “classic” approach and we will follow that more closely

  7. Traditional hypothesis for how the three domains of life are related

  8. An alternative hypothesis for how the three domains of life are related

  9. A tentative phylogeny of eukaryotes (Campbell 6th Edition) We are going to look at protists using a more ‘Classic”, simpler scheme

  10. First a couple definitions • Plankton • Communities of organisms, mostly microscopic, that drift passively or swim weakly near the surface of oceans, ponds, and lakes • Encystment • Cyst formation • A response to adverse conditions • Allows a parasitic species to survive outside a host, allows others to survive hostile environmental conditions • Only some protists can do this

  11. Archezoans • Lack mitochondria or chloroplasts • Have prokaryotic-like ribosomes • Simple cytoskeletons

  12. Archezoans Giardia lamblia Unicellular flagellate. Most commonly transmitted in the cyst form through water contaminated with human feces

  13. Trichomonas vaginalis An inhabitant of vaginal tract of human females. Can be sexually transmitted. Has flagella and an undulating membrane for movement

  14. The Protozoa (animal-like protists) • Diverse group of heterotrophic protists • Classically grouped into different Phyla based upon their movement and how they feed

  15. The Protozoa Rhizopoda – the amoebas • Very simple protists, unicellular • Pseudopodia • Entamoeba histolytica • ( human pathogen)

  16. Amoeba proteus

  17. Use of pseudopodia for feeding

  18. The Protozoa Actinopoda – (Helizoans and Radiozoans) • Axopodia = projections reinforced by bundles of microtubules thinly covered by cytoplasm • Most are planktonic • Heliozoans – fresh water • Radiozoans- marine, silica shells

  19. Actinopods: Heliozoan (left), radiolarian (right)

  20. Radiolarian skeleton

  21. The Protozoa Foraminifera (Forams) • Marine organisms • Porous shells of organic material hardened by calcium carbonate • Many have algae living beneath the shell which provide nutrients via photosynthesis

  22. Foraminiferan

  23. The Protozoa Apicomplexa (Sporozoans) • All species are obligate intracellular parasites of animals • Toxoplasma gondii • Toxoplasmosis • Cryptosporidium • Diarrhea. Transmitted via fecal contamination • Water supply outbreaks have been reported • Plasmodium • Malaria

  24. The two-host life history of Plasmodium, the apicomplexan that causes malaria

  25. The Protozoa Zoomastigophora (flagellates) • Move by whip-like flagella • Trichonympha • Inhabits the gut of termites • Trypanosoma • Hemoflagellate • African Sleeping sickness

  26. Trichonympha

  27. Trypanosoma, the kinetoplastid that causes sleeping sickness

  28. The Protozoa Ciliophora (ciliates) Stentor Paramecium • Move by cilia • Most are free-living in fresh water • Paramecium • Stentor • Vorticella Vorticella

  29. Ciliates: Paramecium

  30. Fungus-like Protists • Filamentous body structure at times makes them appear to be like molds, but they are more closely related to amoebas than to true fungi. • Myxomycota (plasmodial slime molds) • Acrasiomycota (cellular slime molds) • Oomycota (water molds, white rusts, downy mildews)

  31. The life cycle of a plasmodial slime mold, such as Physarum

  32. Plasmodial slime mold

  33. Slime mold Sporangia

  34. The life cycle of a cellular slime mold (Dictyostelium)

  35. Dictyostelium life cycle

  36. Stages of Dictyostelium

  37. The life cycle of a water mold (Layer 3)

  38. Water mold: Oogonium

  39. Powdery mildew

  40. Algae • Diverse group of photoautotrophic aquatic organisms • Major role in aquatic food chains • Fix carbon dioxide into organ carbon • Produce somewhere between 50% and 80 % of the Earth’s oxygen

  41. AlgaeDinoflagellata (dinoflagellates) • They have two flagella and may have armor (cellulose plates) or may be naked (without armor). Dinoflagellates have pigments and can carry on photosynthesis. Major component of phytoplankton. • Gonyaulax • Red tide • Paralytic shellfish poisoning • Peridinium (lab) • Noctiluca miliaris • Bioluminescent

  42. Dinoflagellate

  43. Dinoflagellates

  44. Swimming with bioluminescent dinoflagellates

  45. AlgaeBacillariophyta (Diatoms)

  46. a diatom, a unicellular "alga"

  47. Chrysophyta Golden algae

  48. Phaeophyta (Brown algae) • Largest and most complex of the algae • Kelp is a brown algae • Giant kelp - up to 100 meters in size • Seaweeds = large, multicellular marine algae of coastal waters which include members of the Brown, Red, and Green algae groups

  49. Australian bull kelp (Durvillea potatorum)

  50. Kelp forest

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