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Chapter 12

Chapter 12. Characterizing and Classifying Eukaryotes. Eukaryotes. Four major groups Protozoa Fungi Algae Water molds and slime molds Include both human pathogens and organisms vital for human life. Reproduction in Eukaryotes. More complicated than that in prokaryotes

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Chapter 12

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  1. Chapter 12 Characterizing and Classifying Eukaryotes

  2. Eukaryotes • Four major groups • Protozoa • Fungi • Algae • Water molds and slime molds • Include both human pathogens and organisms vital for human life

  3. Reproduction in Eukaryotes • More complicated than that in prokaryotes • Eukaryotic DNA packaged as chromosomes in the nucleus • Have variety of methods of asexual reproduction (budding, fragmentation, spore formation, and schizogony) • Many reproduce sexually by forming gametes and zygotes • Algae, fungi, and some protozoa reproduce sexually and asexually

  4. Classification of Eukaryotic Organisms Figure 12.4

  5. Protozoa • Diverse group defined by three characteristics • Eukaryotic • Unicellular • Lack a cell wall • With exception of the group apicomplexans, they are motile by means of cilia, flagella, and/or pseudopodia

  6. Distribution of Protozoa • Require moist environments • Most live worldwide in ponds, streams, lakes, and oceans; critical members of plankton • Others live in moist soil, beach sand, and decaying organic matter • Very few are pathogens

  7. Morphology of Protozoa • Characterized by great morphologic diversity • Some have two nuclei • Macronucleus contains many copies of genome – controls metabolism, growth, and sexual reproduction • Micronucleus – involved in genetic recombination, sexual reproduction, and regeneration of macronuclei • Variety in number and kinds of mitochondria • All produce trophozoites; some produce cysts

  8. Life Cycle of Parasitic Protozoans • consists of two stages: trophozoite(motile feeding stage) and cyst (resting stage) • under certain adverse conditions, some trophozoites produce a protective cyst. • this cyst enables parasitic species to survive outside of a host

  9. Nutrition of Protozoa • Most are chemoheterotrophic • Obtain nutrients by phagocytizing bacteria, decaying organic matter, other protozoa, or the tissues of host • Few absorb nutrients from surrounding water • Dinoflagellates and euglenoids are photoautrophic

  10. Reproduction in Protozoa • Most reproduce asexually only (binary fission or schizogony) • Few also have sexual reproduction • Some become gametocytes that fuse with one another to form diploid zygote • Some utilize a process called conjugation

  11. Characteristics of Protozoa Table 12.2

  12. Classification • Protozoans are often classified into four groups based on mode of locomotion: • Sarcodina (pseudopodia) • Mastigophora (flagella) • Ciliophora (cilia) • Sporozoa (non-motile)

  13. Sarcodina • Move and feed by pseudopodia using amoeboid motion

  14. Entamoebahistolytica • lobe-shaped pseudopodia • no shell • some are disease causing • Ex. Entamoebahistolytica • live inside animals • cause of amebic dysentarythrough thelysis of human intestinal cells • infection occurs through ingestion of drinking water with contaminated feces, hands, food, or oral-anal intercourse • Annual mortality of 100,000

  15. Classification • Protozoans are often classified into four groups based on mode of locomotion: • Sarcodina (pseudopodia) • Mastigophora (flagella) • Ciliophora (cilia) • Sporozoa (non-motile)

  16. Mastigophora • move by flagella

  17. Giardiaintestinalis • Diarrhea-causing pathogen (giardiasis) • Spread in the cyst form in fecal contaminated water, food, soil.

  18. Trichomonasvaginalis • Most common protozoan disease (trichomoniasis) • Transmitted via sex • Occurs most frequently in people with a preexisting STD

  19. Trypanosoma • Hemoflaggellates: blood parasite • Ex. Trypanosome: causative agent of African Sleeping sickness • Transmitted by the tse-tse fly

  20. Life cycle of Trypanosomabrucei, causative agent of African sleeping sickness

  21. Dinoflagellates • Unicellular • Photoautotrophs • also considered protozoans • Freshwater and marine plankton • Two flagella of unequal length

  22. Red Tide • Some dinoflagellates produce red pigment • An abundance of these organisms produces “red tide” • Red tide blooms produce neurotoxins that are toxic to marine life

  23. Red Tide

  24. Pfiesteria • Dinoflagellate • Poisons people who handle infected fish or inhalation of microbes

  25. BAD DINOFLAGELLATES:PARALYTIC SHELLFISH POISONING Red Tide strikes again DEP shuts down shellfish harvesting in waters of Bay and Gulf counties News Herald Staff Report State environmental officials closed Bay County and Gulf County waters to shellfish harvesting Thursday after detecting unacceptable levels of red tide. Water samples taken from Mexico Beach showed medium levels of red tide - about 933,000 cells per liter. DEP shuts down shellfish harvesting when levels reach 5,000 cells per liter.

  26. Classification • Protozoans are often classified into four groups based on mode of locomotion: • Sarcodina (pseudopodia) • Mastigophora (flagella) • Ciliophora (cilia) • Sporozoa (non-motile)

  27. Balantidium coli • human parasite that causes a rare type of severe dysentery (Balantidiasis) • ingested as cysts, they enter the intestine and trophozoitesare released • the trophozoites destroy host cells and feeds on the host cell fragments

  28. Classification • Protozoans are often classified into four groups based on mode of locomotion: • Sarcodina (pseudopodia) • Mastigophora (flagella) • Ciliophora (cilia) • Sporozoa (non-motile)

  29. Sporozoans (Apicomplexans) • Animal pathogens • Adults are non-motile • Ex. Plasmodium (Genus) – causative agent of malaria

  30. Eukaryotes • Four major groups • Protozoa • Fungi • Algae • Water molds and slime molds • Include both human pathogens and organisms vital for human life

  31. Fungi • Chemoheterotrophic • Decompose dead organisms and recycle their nutrients • Have cell walls typically composed of chitin • Related to animals • Important research tools

  32. Significance of Fungi • Form beneficial associations with roots of vascular plants that help plant absorb water and minerals • Used for food and in manufacturing of foods and beverages • Produce antibiotics • 30% cause diseases of plants, animals, and humans • Can spoil fruit, pickles, jams, and jellies

  33. Nutrition of Fungi • Acquire nutrients by absorption • Most are aerobic; some are anaerobic; many yeasts are facultative anaerobes

  34. Fungal Morphology • the body of fungi is termed thallus(non-reproductive) • The thalli of yeast are small, globular and are single celled • The thalli of mold are composed of long, branched tubular filaments called hyphae.

  35. Fungal Morphology • Within multi-ceullarhyphae of molds, the can either be separated (septae) or continuous (aseptate)

  36. Fungal Morphology • Some members of fungi are dimorphic. • They take either a globular form or filamentous form depending on environmental conditions.

  37. Reproduction of Fungi • All have some means of asexual reproduction • Yeasts bud in manner similar to prokaryotic budding • Filamentous fungi produce lightweight spores that differ in mode of development • Most also reproduce sexually

  38. Budding and Asexual Spore Formation • Budding:

  39. Asexual Spores of Molds • Some asexual spores are enclosed in sacs called sporangium at the end of the hyphae. Figure 12.19a

  40. Asexual Spores of Molds • Some asexual spores are located in the middle of the hyphae and enclosed in a thick wall (chlamydiospores).

  41. Asexual Spores of Molds • Some asexual spores called conidaare not enclosed in sacs at the end of the hyphae.

  42. Asexual Spores of Molds • The type of asexual spore produced by a mold is often used clinically to identify the identity of the mold pathogen.

  43. Sexual Spores Formation

  44. Eukaryotes • Four major groups • Protozoa • Fungi • Algae • Water molds and slime molds • Include both human pathogens and organisms vital for human life

  45. Algae • Simple, eukaryotic, phototrophic organisms that carry out oxygenic photosynthesis. • Reproduce asexually and sexually. • Differ widely in distribution, morphology, reproduction, and biochemical traits

  46. Distribution and Morphology of Algae • Most are aquatic, living in the photic zone of fresh, brackish, and salt water • Unicellular, colonial, or have simple multicellular bodies (thalli)

  47. Classification of Various Algae Table 12.4

  48. Red Algae Figure 12.29

  49. Diatom • Single-celled • Silicon in cell walls composed of two halves • Major component of phytoplankton • Major source of world’s O2 Figure 12.32

  50. Brown Algae Figure 12.31

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