1 / 38

Chapter 12

Chapter 12. Characterizing and Classifying Eukaryotes. Five major groups of eukaryotic microbes: Protozoa Fungi Algae Water molds Slime molds Include both human pathogens and organisms vital for human life. General Characteristics of Eukaryotic Organisms. Reproduction in Eukaryotes

martinezdonna
Download Presentation

Chapter 12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 12 Characterizing and Classifying Eukaryotes

  2. Five major groups of eukaryotic microbes: • Protozoa • Fungi • Algae • Water molds • Slime molds • Include both human pathogens and organisms vital for human life

  3. General Characteristics of Eukaryotic Organisms • Reproduction in Eukaryotes • More complicated than that in prokaryotes • Eukaryotic DNA packaged with histones as chromosomes in the nucleus • Have variety of methods of asexual reproduction • Budding • Fragmentation • spore formation • Schizogony (discussed later) • Many reproduce sexually by forming gametes and zygotes • Algae, fungi, and some protozoa reproduce both sexually and asexually

  4. General Characteristics of Eukaryotic Organisms • Reproduction in Eukaryotes • Nuclear division • Nucleus has one or two complete copies of genome • Single copy – haploid (most fungi, many algae, some protozoa) • Two copies – diploid (remaining fungi, algae, and protozoa) • Two types • Mitosis • Meiosis

  5. Reproduction in Eukaryotes • Nuclear division • Mitosis • Begins after cell has duplicated its DNA; cell partitions replicated DNA equally between two nuclei • Maintains ploidy of parent nucleus • Four phases • Prophase • Metaphase • Anaphase • Telophase

  6. Reproduction in Eukaryotes • Cytokinesis (cytoplasmic division) • Typically occurs simultaneously with telophase of mitosis • In some algae and fungi, may be postponed or not occur at all • Results in multinucleated cells called coenocytes

  7. [INSERT FIGURE 12.2]

  8. Shizogony-some protozoa, like Plasmodium-asexual reproduction-multiple mitosises followed then by cytokinesis [INSERT FIGURE 12.3]

  9. Classification system is changing [INSERT FIGURE 12.4]

  10. Protozoa • Diverse group defined by three characteristics • Eukaryotic • Unicellular • Lack a cell wall and most (but not all) are heterotrophic • Motile by means of cilia, flagella, and/or pseudopodia (except subgroup, apicomplexans) • 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

  11. Protozoa • 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 • Some have contractile vacuoles – maintains osmoregulation • All aquatic pathogenic protozoa produce trophozoites • Motile feeding stage • some produce cysts • Hardy resting stage

  12. Protozoa • 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

  13. Protozoa • Reproduction in Protozoa • Most reproduce asexually only (binary fission or schizogony) • Few also have sexual reproduction

  14. Protozoa [INSERT TABLE 12.2]

  15. Protozoan Classification • Parabasala • Lack mitochondria • includesTrichomonas • Diplomonadida • Lack mitochondria, Golgi, peroxisomes • Includes Giardia • Euglenozoa • Euglenids – share characteristics of both plants and animals (chloroplasts and flagella) • Kinetoplastids – single mitochondria • includesTrypanosoma • Aveolates • 3 subgroups: • Apicomplexans – pathogens of animals (includes Plasmodium, Toxoplasma) • Dinoflagellates – photosynthetic but molecular data show they are more closely related to ciliates than algae • Ciliates – have cilia ( includes Vorticella, Paramecium) • Amoebae – have pseudopodia, little uniformity in this group • Rhizaria – threadlike pseudopodia – include foraminiferans, radiolarians • Amoebozoa – include amoebas • Can cause disease in eyes and brains of animals • Includes slime molds • Plasmodial – acellular, filaments of cytoplasm • Cellular slime molds

  16. Protozoa [INSERT FIGURE 12.14]

  17. Fungi • Chemoheterotrophic • Have cell walls typically composed of chitin • Lack chlorophyll; do not perform photosynthesis • Cytokinesis does not always happen after mitosis resulting in coenocytes (multiple nuclei) • Related to animals • The Significance of Fungi • Decompose dead organisms and recycle their nutrients • Form associations with roots of vascular plants, which help plants absorb water and minerals • Used for food and in manufacture of foods and beverages • Produce antibiotics • Serve as important research tools • 30% cause diseases of plants, animals, and humans • Can spoil fruit, pickles, jams, and jellies

  18. Fungi [INSERT FIGURE 12.16]

  19. Fungi • Nutrition of Fungi • Acquire nutrients by absorption • Most are saprobes (secrete enzymes into environment to degrade) • Some trap and kill microscopic soil-dwelling nematodes • Haustoria (slender projections) allow some to derive nutrients from living plants and animals • Most are aerobic; some are anaerobic; many yeasts are facultative anaerobes

  20. Fungi • Reproduction in Fungi • All have some means of asexual reproduction involving mitosis and cytokinesis • Asexual spores are classified by their mode of development (the structures which they are derived from) • Most also reproduce sexually

  21. Fungi • Reproduction in Fungi • Budding and asexual spore formation • Yeasts bud in manner similar to prokaryotic budding • Pseudohypha – series of buds that remain attached to one another and to parent cell

  22. Fungi [INSERT FIGURE 12.19]

  23. Fungi • Classification of Fungi • Division Zygomycota • Division Ascomycota • Division Basidiomycota • Deuteromycetes

  24. Fungi • Classification of Fungi • Deuteromycetes • Heterogeneous collection of fungi whose sexual stages are unknown • rRNA analysis revealed that most deuteromycetes belong in the division Ascomycota

  25. Fungi • Lichens • Partnerships between fungi and photosynthetic microbes (green algae or cyanobacteria) • Abundant throughout the world, particularly in pristine habitats • Grow on soil, rocks, leaves, tree bark, other lichens, and even on backs of tortoises, in almost every habitat • Occur in three basic shapes – fruticose, crusts, foliose • Important in creation of soil from rocks • Eaten by many animals

  26. Fungi [INSERT FIGURE 12.26]

  27. Fungi [INSERT TABLE 12.3]

  28. Algae • Simple, eukaryotic, phototrophic organisms that carry out oxygenic photosynthesis using chlorophyll a • Have sexual reproductive structures; every cell becomes a gamete • Differ widely in distribution, morphology, reproduction, and biochemical traits • Distribution of Algae • Most are aquatic, living in the photic zone of fresh, brackish, and salt water • Have accessory photosynthetic pigments that trap energy of light and pass it to chlorophyll a

  29. Algae • Morphology of Algae • Unicellular (phytoplankton), colonial, or have simple multicellular bodies (“seaweed”)

  30. Algae • Reproduction in Algae • Asexual reproduction in unicellular algae involves mitosis followed by cytokinesis • Unicellular algae that reproduce sexually form zygotes from individual gametes; zygote undergoes meiosis • Multicellular algae may reproduce asexually by fragmentation • Many multicellular algae reproduce sexually with alternation of generations

  31. Algae [INSERT TABLE 12.4]

  32. Other Eukaryotes of Microbiological Interest: Parasitic Helminths and Vectors • Parasitic worms have microscopic infective and diagnostic stages – usually eggs or larvae • Arthropod vectors are animals that carry pathogens • Mechanical vectors • Biological vectors • Disease vectors belong to two classes of arthropod • Arachnida • Insecta

  33. Other Eukaryotes of Microbiological Interest: Parasitic Helminths and Vectors • Arachnids • Adult arachnids have four pairs of legs • Ticks are the most important arachnid vectors • Hard ticks are most prominent tick vectors • A few mite species transmit rickettsial diseases

  34. Other Eukaryotes of Microbiological Interest: Parasitic Helminths and Vectors • Insects • Adult insects have three pairs of legs and three body regions • Include • Fleas • Lice • Flies • Mosquitoes

More Related