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Biology 1030 Winter 2009 Microorganisms Chapter 17 (556-560, 564-565) Chapter 31 (608-623) Chapter 28 (549-569) Scott circa 2009 Microorganisms • • • • Bacteria Cyanobacteria Fungi Protists Scott circa 2009 1 Biology 1030 Winter 2009 Bacteria Are Wee 1 mm = 1000000 • Largest prokaryote is Epulopiscium fishelsoni – 600 μm !!! (= 0.6 mm) 100000 Size (nm) • Average bacteria range from 1-5 μm 10000 • Smallest bacteria are the Mycoplasma 1 μm = 1000 – 120-250 nm 100 Scott circa 2009 Bacterial Cell Shapes • Coccus – Staphylococcus aureus • Bacillus – Escherichia coli • Coccobacillus – Brucella abortus • Spiral – Helicobacter pylori • Pleomorphic (many forms) – Mycobacteria – Lack a rigid cell wall Scott circa 2009 2 Biology 1030 Winter 2009 Bacterial Arrangements • Pairs – Neisseria gonorrhoeae • Clusters – Staphylococcus aureus • Chains – Streptococcus pneumoniaea • Random Scott circa 2009 Bacterial Structures Cell wall • Cell Membrane • Cell Wall Nucleoid – Outer membrane • Internal Structures – Nucleoid – Ribosomes Capsule Sex pilus Fimbriae • External Structures – Capsule – Pili – Flagella • No organelles Flagella Scott circa 2009 3 Biology 1030 Winter 2009 Cell Division in Bacteria • Binary fission – Continuous DNA synthesis – Continuous growth Scott circa 2009 Cyanobacteria • Photosynthetic prokaryotes • Internal membrane structures • Anabaena • Heterocysts – Nitrogen fixation Scott circa 2009 4 Biology 1030 Winter 2009 Nucleariids • Predecessor to all fungi • An opisthokont protist Scott circa 2009 The Fungi • Not just mushrooms! • Hyphae – Tubular – Branched • Mycelium – Aggregation • Animal-like – Cell walls – Glycogen – Fats Scott circa 2009 5 Biology 1030 Winter 2009 Biology of Fungi • Absorptive heterotrophs – Saprophytic • Parasitic • Predatory – Arthrobotrys Scott circa 2009 Fungal Life Cycle • Haplontic life cycle PLASMOGAMY (fusion of cytoplasm) KARYOGAMY ((fusion of nuclei)) Spore producing Spore-producing structures Spores Heterokaryotic stage ASEXUAL Mycelium REPRODUCTION SEXUAL REPRODUCTION Zygote MEIOSIS GERMINATION – – – – Diploid zygote Haploid spores Haploid mycelium Plasmogamy • Heterokaryotic – Karyogamy GERMINATION Spores But … Some are diplontic Some are haplodiplontic Scott circa 2009 6 Biology 1030 Winter 2009 Fungal Spores • Common reproductive cell • Produced by: – Meiosis – sexual – Mitosis – asexual Mycelia • Divide by mitosis Zygosporangium KARYOGAMY Sporangia Spores Sporangium Diploid nuclei MEIOSIS Mycelium Scott circa 2009 Fungal Gametes • Mitosis • Heterokaryotic mycelium • Isogametes – + versus – Mating type (+) PLASMOGAMY Gametangia with haploid nuclei Mating type (–) Young zygosporangium (heterokaryotic) Zygosporangium Scott circa 2009 7 Biology 1030 Winter 2009 Fungal Phyla • • • • • Chytridiomycota Zygomycetes Glomeromycetes Ascomycetes Basidiomycetes Scott circa 2009 Phylum Chytridiomycota • Ancestral fungi • Most are aquatic • Flagella – Gametes – Zoospores • No mycelia y – Rhizoids Scott circa 2009 8 Biology 1030 Winter 2009 Phylum Zygomycetes • Aseptate hyphae – Coenocytic • Asexual reproduction – Spores released from sporangia • Sexual reproduction – – and + strains combine – Resilient zygosporangium – Karyogamy & meiosis • Black bread mold (Lab 6) Scott circa 2009 Phylum Glomeromycetes • Very small group • Very significant group • Arbuscular mycorrhizae – 90-95% of plants Scott circa 2009 9 Biology 1030 Winter 2009 Phylum Ascomycetes • Septate hyphae • The sac fungi – Fruiting bodies Ascocarp – Sporangia (asci) • Meiosis • Mitosis • 8 ascospores • Asexual spores – Conidia Scott circa 2009 Phylum Basidiomycetes • Septate hyphae • The club fungi – Fruiting bodies Basidiocarp – Sporangia (basidia) • Meiosis • 4 basidiospores • Long Long-lived lived dikaryotic stage Scott circa 2009 10 Biology 1030 Winter 2009 Decomposition • Saprophytic – Non-living food source • Leaf litter – Locked in nutrients – Insoluble Scott circa 2009 Extracellular Digestion • Hydrolytic enzymes • Absorptive heterotrophs Scott circa 2009 11 Biology 1030 Winter 2009 Parasitic Fungi • Heterotroph – Living organisms (host) • Dutch elm disease – Mycelium infects xylem – Scarring • Athletes foot Scott circa 2009 Practical Mycology • Antibiotics – 3R*,4S*,5S*,6R*,7R*, 9R*,11R*, 12R*,13S*,14R*)-4-[(2,6-Dideoxy-3-C-methyl-3-O-methylα-L-ribo-hexopyranosyl)-oxy]-14-ethyl-7,12,13-trihydroxy-3, 5, 7, 9,11,13-hexamethyl-6[[3 4 6 trideoxy 3 (dimethylamino) β D xylo hexopyranosyl]oxy]oxacyclotetradecane [[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]oxacyclotetradecane2,10-dione • Food Scott circa 2009 12 Biology 1030 Winter 2009 Autotrophic Protists • Photosynthetic – Algae • All have chloroplasts – Source? Scott circa 2009 Euglenoids • Plant-like • Animal-like – Chloroplasts – Photosynthesis – No cell wall – Ingest nutrients Mixotrophs Long flagellum Eyespot Short flagellum Contractile vacuole Chloroplast Plasma membrane Pellicle Scott circa 2009 13 Biology 1030 Winter 2009 Evolution of Eukaryotes • Prokaryotic ancestor • Plasma membrane invaginates – Remember Anabaena • Internal membranes – Endomembrane theory Scott circa 2009 Endosymbiotic Theory • Serial endosymbiosis • Two possible mechanisms 1. Ingest but don’t kill 2. Infect but don’t kill • First event y – Heterotrophic prokaryote – Mitochondrion Scott circa 2009 14 Biology 1030 Winter 2009 Endosymbiotic Theory • Second event – Autotrophic prokaryote – Chloroplast Scott circa 2009 Endosymbiotic Theory • Third event – Autotrophic eukaryote – Chloroplast • Evidence? Scott circa 2009 15 Biology 1030 Winter 2009 The Algae • Grouped by ‘colour’ • Pigments in chloroplast – Chlorophyll a – Accessory pigments • Fucoxanthin Brown Algae Phycoerythrin Red Algae Chlorophyll b Green Algae Scott circa 2009 Algal Structure • Overall structure – Similarities to the land plants • Blades – No true leaves • Stipe – No true stems • Holdfast – No true roots Scott circa 2009 16 Biology 1030 Winter 2009 Algal Structure • Predecessor of land plants • Land plant – Many similarities – Structure and function • Cosmarium Cell Wall Plasma Membrane Nucleus Plant Vacuole Chloroplast Pyrenoid Scott circa 2009 Algal Life Cycles • Haplontic or Alternation of generations – No heterokaryotic stage • Chlamydomonas Gametes (n) – – + + Zoospore FERTILIZATION Mature cell (n) Zygote (2n) MEIOSIS Scott circa 2009 17 Biology 1030 Winter 2009 Lichens • Symbioses • Mycobiont – Ascomycetes • Photobiont – Alga, cyanobacteria Scott circa 2009 18
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