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Intro to Prokaryotes Lecture 1 Spring 2014 Meet the Prokaryotes 1 Meet the Prokaryotes 2 Meet the Prokaryotes Why study prokaryotes? 3 Deep Time Fig. 25.7 When did Prokaryotes evolve? Stromatolites – rocklike structures of bacteria and sediment 4 Fossilized stromatolite (above) and living stromatolite (below) Deep Time 5 • How did early prokaryotes produce ATP? • Evolution of electron transport systems ~ 3 bya • Development of atmospheric oxygen ~ 2.7 bya Fig. 25.7 6 Deep Time • Evolution of eukaryotes~ 2.1 bya Fig. 25.8 The New Tree of Life Phylogeny - the evolutionary history of a species or group of related species Taxonomy • Ordered division of organisms into categories 7 The New Tree of Life Prokaryotes Eukaryotes 8 The New Tree of Life 9 Fig. 26.21 10 Review 1. Draw an animal cell. Label structures w/name and function 2. Make a list of the differences between plant and animal cells 3. Make a list of the differences between prokaryotes and eukaryotes Eukaryotes: Animal Cells Animal cell structures: • Plasma membrane • Nucleus • Cytosol • Ribosomes • Endoplasmic reticulum • Golgi apparatus • Mitochondria • Cytoskeleton • Vacuoles • Peroxisome Not typically found in plants: • Centrosome • Lysosomes • Flagella See Fig. 6.9 –Animal cell 11 Eukaryotes: Plant Cells Plant cell structures: • Plasma membrane • Nucleus • Cytosol • Ribosomes • Endoplasmic reticulum • Golgi apparatus • Mitochondria • Cytoskeleton • Peroxisome Not found in animals: • Cell Wall w/plasmodesmata • Plastids (Chloroplasts, Amyloplasts, Chromoplasts) • Central vacuole Fig. 4.6 –Animal cell See Fig. 6.9 – Plant cell 12 Prokaryotes Bacteria • Cannot grow above 100˚C Archaea • Extremophiles – thermophiles – halophiles 13 Prokaryotes Prokaryotes: Domain Bacteria & Archaea • Unicellular • Colonial or solitary • Small 14 15 Structure: Shapes Prokaryotes can be described by shape • coccus, bacillus, spirillum Colonies can be described by how cells are aggregated • strepto = in chains – e.g., streptobacilli • staphylo = in clusters – e.g., staphylococci (spirillum) Fig. 27.2 Structure: Cell Walls Function of cell walls? Eukaryotes •Which eukaryotes have cell walls? •What is the major structural components for each? Bacteria •Peptidoglycan •Classification – gram-positive and gram-negative Archaea •Lack peptidoglycan •Contain other polysaccharides & proteins 16 Structure: Bacterial Cell Walls 17 Lipopolysaccharides . See Fig. 27.3 18 Gram-positive & Gram-negative Why does this classification matter? • Within group of pathogenic (disease-causing) bacteria, gram-negative more threatening than gram-positive. Gram-positive & Gram-negative Gram-negative • Toxic lipopolysaccarides • Outer membrane defends bacteria against a body’s defense system • Antibiotic resistance – reduces/prevents drug entry – targeted to peptidoglycan layer 19 2 21 22 Structures for Attachment • Capsules – Slime layer • Fimbriae • Pili Fig. 27.4 Fimbriae Fig. 27.12 Fig. 27.5 Structures for Movement • Taxis Fig. 27.6 23 Structure: Internal Organization Fig. 27.7 24 Structure: Internal Organization Plasmids • a small ring of DNA carrying accessory gene Prokaryotic chromosome • Ring - few proteins Fig. 27.8. 25 Metabolic Diversity 26 Metabolic Diversity: Oxygen • Obligate aerobes • Obligate anaerobes – Fermentation or – Anaerobic respiration Facultative anaerobes 27 28 • How can the metabolic capabilities of bacteria help us solve environmental problems? • Show movie 29 Toxins in the environment • Bioaccummulation • Biomagnification Bioremediation • use of biological processes to degrade, transform, and/or remove contaminants from soil and water 30 Phytoremediation • Use of plants for on-site treatment of contaminated soils, sediments, and water – Hyperaccumulators • E.g., cadmium, lead, arsenic, zinc 31 Phytoremediation – Phytoremediaton & genetic engineering • Bacteria gene to transform methylmercury 32 Metabolic Diversity: Unique Capabilities Nitrogen fixation & Denitrification Fig. 54.17 33 Ecological Roles of Prokaryotes Critical for the survival of life on earth • • • • Carbon cycle Oxygen Nitrogen cycle Decomposers Fig. 54,17 34 Ecological Roles: Symbiotic Relationships between prokaryotes & eukaryotes • Mutualism Host = fish Symbiont = bacteria inside fish Fig. 27.15 35 Ecological Roles: Mutualism • Humans & Bacteroides thetaiotamicron • Nitrogen fixing in plants – Rhizobium spp. and plants from Legume family 36