Chapters 19 & 20

1. Layers of a bacterial mat Chapters 19 & 20 0 The Origin and Evolution of Microbial Life: Prokaryotes and Protists How Ancient Bacteria Changed the World • Mounds of rock found near the Bahamas contain photosynthetic prokaryotes • Fossilized mats 2.5 billion years old mark a time when photosynthetic prokaryotes were producing enough O2 to make the atmosphere aerobic

2. EARLY EARTH AND THE ORIGIN OF LIFE Life began on a young Earth • Planet Earth formed some 4.6 billion years ago • The early atmosphere probably contained • H2O, CO, CO2, N2, and some CH4 • Volcanic activity, lightning, and UV radiation were intense • Fossilized prokaryotes called stromatolites date back 3.5 billion years

3. Membrane RNA Polypeptide LM 650 • Membranes may have separated various aggregates of self-replicating molecules • Which could be acted on by natural selection

4. Colorized SEM 650 PROKARYOTES • Prokaryotes have inhabited Earth for billions of years • Prokaryotes are the oldest life-forms and remain the most numerous and widespread organisms Bacteria and archaea are the two main branches of prokaryotic evolution • Domains Bacteria and Archaea are distinguished on the basis of nucleotide sequences and other molecular and cellular features

5. Differences between Bacteria and Archaea

6. Colorized SEM 3,000 Colorized SEM 12,000 Colorized SEM 9,000 Prokaryotes come in a variety of shape • Prokaryotes may be shaped as • Spheres (cocci) • Rods (bacilli) • Curves or spirals

7. Pili Colorized TEM 16,000 Colorized TEM 70,000  Capsule Various structural features contribute to the success of prokaryotes • External Structures • The cell wall is one of the most important features of nearly all prokaryotes, is covered by a sticky capsule • Some prokaryotes • Stick to their substrate with pili

8. Endospore Flagellum Colorized TEM 14,000 Plasmamembrane Cell wall TEM 34,000 Rotary movement ofeach flagellum • Motility • Many bacteria and archaea • Are equipped with flagella, which enable them to move Reproduction and Adaptation • Prokaryotes • Have the potential to reproduce quickly in favorable environments • Some prokaryotes can withstand harsh conditions • By forming endospores

9. Respiratorymembrane Colorized SEM 13,000 TEM 45,000 Thylakoidmembrane TEM 6,000 Metabolic Cooperation • Internal Organization • Some prokaryotic cells have specialized membranes that perform metabolic functions • In some prokaryotes, metabolic cooperation occurs in surface-coating colonies called biofilms

10. Prokaryotes obtain nourishment in a variety of ways • As a group, Prokaryotes exhibit much more nutritional diversity than eukaryotes Types of Nutrition • Autotrophs make their own organic compounds from inorganic sources • Photoautotrophs harness sunlight for energy and use CO2 for carbon • Chemoautotrophs obtain energy from inorganic chemicals instead of sunlight • Heterotrophs obtain their carbon atoms from organic compounds • Photoheterotrophs can obtain energy from sunlight • Chemoheterotrophs are so diverse that almost any organic molecule can serve as food for some species

11. Nutritional classification of organisms

12. Archaea thrive in extreme environmentand in other habitats • Archaea are common in • Salt lakes, acidic hot springs, deep-sea hydrothermal vents • Archaea are also a major life-form in the ocean

13. Nitrogen-fixingcells Colorized SEM 2,8000 LM 650 Colorized TEM 5,000 Photosyntheticcells LM 13,000 Bacteria include a diverse assemblage of prokaryotes • Bacteria are currently organized into several subgroups, including Proteobacteria Chlamydias Spirochetes Gram-positive bacteria Cyanobacteria, which photosynthesize in a plantlike way

14. Tick that carriesthe Lyme diseasebacterium SEM 2,800 Spirochetethat causesLyme disease SEM 12,000 “Bull’s-eye”rash • Some bacteria cause disease • Pathogenic bacteria cause disease by producing exotoxins or endotoxins Bacteria can be used as biological weapons • Bacteria, such as the species that causes anthrax can be used as biological weapons

15. Rotatingspray arm Rock bed coated withaerobicbacteriaand fungi Outflow Liquid wastes Prokaryotes help recycle chemicals and clean up the environment • Bioremediation • Is the use of organisms to clean up pollution • Prokaryotes are decomposers in • Sewage treatment and can clean up oil spills and toxic mine wastes

16. PROTISTS • The eukaryotic cell probably originated as a community of prokaryotes • Eukaryotic cells • Evolved from prokaryotic cells more than 2 billion years ago • The nucleus and endomembrane system • Probably evolved from infoldings of the plasma membrane • Mitochondria and chloroplasts • Probably evolved from aerobic and photosynthetic endosymbionts, respectively

17. Fungi Ciliates Plants Diatoms Animals Amoebas Red algae Water molds Green algae Diplomonads Brown algae Apicomplexans Euglenozoans Dinoflagellates Choanoflagellates Cellular slime molds Plasmodial slime molds Closest algal relatives of plants Amoebozoa Alveolates Stramenopila LM 275 Ancestral eukaryote Protists are an extremely diverse assortment of eukaryotes • Protists are mostly unicellular eukaryotes • Molecular systematics is exploring eukaryotic phylogeny A tentative phylogeny of eukaryotes includes multiple clades of protists. The taxonomy of protists is a work in progress

18. Colorized SEM 1,300 Colorized SEM 1,300 Colorized SEM 4,000 Diplomonads and Euglenozoans include some flagellated parasites • The parasitic Giardia • Is a diplomonad with highly reduced mitochondria • Euglenozoans • Include trypanosomes and Euglena

19. Cilia Macronucleus TEM 26,000 Apex SEM 2,300 LM 60 Red blood cell • Alveolates have sacs beneath the plasma membrane and include dinoflagellates, apicomplexans, and ciliates • Dinoflagellates • Are unicellular algae • Apicomplexans are parasites • Such as Plasmodium, which causes malaria • Cilliates • Use cilia to move and feed

20. LM 400 • Stramenopiles are named for their “hairy” flagella and include the water molds, diatoms, and brown algae • This clade includes fungus-like water molds • Photosynthetic, unicellular diatoms • Brown algae, large complex seaweeds

21. LM 185 • Amoebozoans have pseudopodia and include amoebas and slime molds • Amoebas move and feed by means of pseudopodia • A plasmodial slime mold is a multinucleate plasmodium • That forms reproductive structures under adverse conditions

22. 45 Slug-like aggregate LM 1,000 Amoeboid cells Reproductivestructure 15 • Cellular slime molds • Have unicellular and multicellular stages

23. Chlamydomonas Volvox colonies LM 1,200 LM 80 Red algae and green algae are the closest relatives of land plants • Red algae contribute to coral reefs • Green algae • May be unicellular, colonial, or multicellular

24. Mitosis Malegametophyte Spores Gametes Mitosis Femalegametophyte Meiosis Fusion ofgametes Sporophyte Zygote Key Mitosis Haploid (n) Diploid (2n) The life cycles of many algae • Involve the alternation of haploid gametophyte and diploid sporophyte generations

25. Gamete Locomotorcells Somatic cells 2 3 1 Food-synthesizingcells Unicellular protist Colony Early multicellular organismwith specialized, interdepen-dent cells Later organism thatproduces gametes Multicellularity evolved several times in eukaryotes • Multicellularity evolved in several different lineages • Probably by specialization of the cells of colonial protists • Multicellular life arose over a billion years ago

26. What are some things that you know about mushrooms? • Would you classify mushrooms as an animal, a plant, or something else? Give reasons for your answer. Nuclei Cell wall Cytoplasm Cross wall Nuclei Cytoplasm Cell wall Hyphae Structure Section 21-1 • 21–1 The Kingdom Fungi • A. What Are Fungi? • B. Structure and Function of Fungi • C. Reproduction in Fungi • D. How Fungi Spread Hyphae With Cross Walls Hyphae Without Cross Walls Name

27. Figure 21-2 The Structure of a Mushroom Section 21-1 Believe it or not, fungi play an important role in your life. The bread you eat, the salad you make, and the medicine that you take when you are sick may include various types of fungi. Fruiting body 1. List as many examples of fungi that you can. 2. How are fungi helpful to humans? 3. How are fungi harmful to humans? Hyphae Mycelium

28. 21–2 Classification of Fungi A. The Common Molds 1. Structure and Function of Bread Mold 2. Life Cycle of Molds B. The Sac Fungi 1. Life Cycle of Sac Fungi 2. Yeasts C. The Club Fungi 1. Life Cycle of Club Fungi 2. Diversity of Club Fungi 3. Edible and Inedible Mushrooms D. The Imperfect Fungi Section 21-2

29. Deuteromycota Zygomycota Ascomycota Basidiomycota Concept Map Section 21-2 Fungi are divided into the phyla includes includes includes includes Common molds Sac fungi Club fungi Imperfect fungi

30. 21–3 Ecology of Fungi A. All Fungi Are Heterotrophs B. Fungi as Decomposers C. Fungi as Parasites 1. Plant Diseases 2. Human Diseases 3. Other Animal Diseases D. Symbiotic Relationships 1. Lichens 2. Mycorrhizae Section 21-3