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Transcript
Kingdom Monera What are PROKARYOTES? They are ancient life forms known as bacteria • No nucleus • No chloroplasts • No mitochondria Two major clades of bacteria Archaebacteria Methanogens Extreme Thermophiles Extreme Halophiles & Eubacteria Cyanobacteria (Blue-green algae) & other Gram negative bacteria Gram positive bacteria TEM of dividing cell Prokaryotes Lack Organelles (w/ 2 membranes) • No nucleus but have DNA & RNA • No chloroplasts but have pigments, thylakoids & enzymes for PS • No mitochondria but have respiratory chain & membranes • Small ribosomes (70S) for protein synthesis Other constituents? Gas vacuoles; Cell walls; Storage molecules for N, P, C Geoclock Origin of life Cyanophytes established early aerobic environments. Evolution of advanced aerobes 2 H2O + CO2 “Primordial ANAEROBIC soup” O2 + CH2O + H2O More conventional geologic time table MYA ERA 2 65 Cenozoic PERIOD DOMINANT LIFE FORM Quaternary Age of angiosperms Tertiary 150 Cretaceous Rise of angiosperms 200 Jurassic Age of cycads Triassic Rise of cycadophytes 300 Permian Rise of conifers 350 Carboniferous Age of lycopods, ferns, sphenopsids; Rise of mosses 400 Devonian Age of vascular plants; 1st seed plants 450 Silurian 1st vascular plants 500 Ordovician Age of eukaryotic algae 600 Cambrian Rise of eukaryotic algae and fungi 250 Mesozoic 4500 Precambrian Rise of prokaryotes Division Cyanophyta Bacteria that are: • Photosynthetic (convert light energy to food) • Produce O2 as a byproduct of photosynthesis • Some produce toxins • Some have capacity to fix N2 into NH4 TEM of dividing cell • Some have formed millions of years old stromatolites as living structures Cyanophytes have changed the path of evolution on earth Things we will cover General features - defining characteristics Developmental lineages – using morphology to understand evolution Ecology – understanding roles in interacting with other species Commercial interests – exploit ecology Evolution – diversity and change over time General features Ancient organisms but well suited to earth’s habitats 2000 species, 150 genera Habitats: virtually everywhere Oceans Soil Epiphytes Freshwater Hotsprings Endophytes Morphological Range: Unicells to complex multicell organisms Cell Walls: Gram negative bacteria Trichodesmium blooms can cover 2x106 km2 and be seen via satellites NASA Diversity Cell Walls Being comprised of only 20% peptidoglycan, the cell wall of Gram-negative bacteria is much thinner than Gram-positive bacteria. Gram-negative bacteria have two unique regions which surround the outer plasma membrane: i) periplasmic space and ii) lipopolysaccharide layer. • periplasmic space separates the outer plasma membrane from the peptidoglycan layer. • lipopolysaccharide layer is adjacent to the exterior peptidoglycan layer General features Pigments - photosynthesis Storage Products • Chlorophyll a • Phycobilins Phycoerythrin Phycocyanin Allophycocyanin Others • Carotenoids • UV absorbing molecules Growth Photosynthesis & Pigments sunlight • Light energy is harvested by the cell • Only specific colors are absorbed • Other colors are reflected back to your eye Chl a Cell thylakoids Chl a Phycobilins Chlorophyll a Tetrapyrrole Ring Phytol Chain Phycobilins Open tetrapyrrole phycoerythrin phycocyanin Photosynthesis & Pigments • Arrangement of light harvesting structure is specific and detailed Chlorophyll a General features Pigments - photosynthesis • Chlorophyll a • Phycobilins Phycoerythrin Storage Products • Starch (C) • Cyanophycin (N) • Poly Pi bodies Phycocyanin Allophycocyanin Others • Carotenoids • UV absorbing molecules Growth Storage products Starch C = black O = red H = white C = green = blue H = red = white P = purple ATP General features What is in a typical cyanophyte cell? DNA & RNA Pigments, thylakoids & enzymes for PS Respiratory chain & membranes Small ribosomes (70S) Cell walls ? Storage molecules for N, P, C ? Floatation? General features Pigments - photosynthesis • Chlorophyll a • Phycobilins Phycoerythrin Storage Products • Starch (C) • Cyanophycin (N) • Poly Pi bodies Phycocyanin Allophycocyanin Others Growth • Every cell can • Multicellular organisms: Fragments regrow “Spores” regrow Akinetes germinate • Branching • Carotenoids True branching • UV absorbing molecules False branching Growth & morphology 1 1 Binary Fission (cell division) 1 1 1 Cell division for unicells: 2 8 4 Produces genetically identical “offspring” or twins Increases the numbers of cells in the population by exponential growth, 2n Divisions may be every 15 to 20 min 16 cells Growth & morphology Unicell populations grow rapidly # cells in population 1200 Cyanotech ponds 900 Starting with 1 cell: 10 rounds of division 600 1,000+ cells 300 0 1 3 5 7 Rounds of cell division 9 It’s not unusual to have 10 6 to 108 cells / mL in “blooms” Developmental lineages Evaluate adult form to gain insight in possible evolutionary processes. Step-by-step acquisition of new traits via genetic change. Examine reproductive cells and other characters as additional data. Useful means to construct evolutionary hypotheses to test with molecular data. Growth & morphology Developmental Lineage #1 Order Chroococcales Genetic change All cells appear virtually identical internally Evolution has taken a simple shape to more complex but related forms: • Multicellular genera Diversity Order Chroococcales Microcystis Merismopedia Growth & morphology 1 colony Coordinated binary fission of all cells in colony Multicellular organisms divide but increase the number of entities in the population 2 colonies Growth & morphology Developmental Lineage #2 Order Chamaesiphonales Evolution has taken a simple shape: • attachment to the substrate • spores released from upper end of cell Growth & morphology Developmental Lineage #3 trichome + sheath Order Nostocales (filament) trichome (no sheath evident) Evolution has taken a simple shape: • constrained cells into chains • formed arrays of trichome(s) in sheaths • false branching can result trichomes + sheath Diversity Order Nostocales Growth & morphology False branching : 1. Rupture of sheath and cells 2. Remaining cells at both ends continue to grow 3. Both trichomes push through weakened sheath What to look for? Is there a change in the plane of cell division? Order Nostocales New Cell Types Order Nostocales Nitrogen fixation supports protein synthesis 1. Low N in environment 2. Cell differentiates as a specialized cell, the heterocyst 3. Creates setting for Nitrogenase enzyme 4. Enzyme converts N2 NH4+ polar heterocysts Growth & morphology Order Nostocales Nitrogen fixation & Azolla in rice fields replace fertilizers 1. Low N in environment 2. Heterocysts differentiate 3. Enzyme converts N2 NH4+ 4. Water fern benefits from fertilizer 5. Rice fields are more productive intercalary heterocysts Other cell types Akinete Anabaena Order Nostocales Cool stuff Order Nostocales Growth & morphology Developmental Lineage #4 Order Stigonematales True branching Evolution has taken a simple shape: • formed arrays of cells that divide in 2 directions (planes) Multiseriate tissues Growth & morphology True branching : 1. No rupture of sheath or cells 2. Cells divide in two planes 3. Create new structures, branches What to look for? Is there a change in the plane of cell division? Order Stigonematales Growth & morphology Complex tissue • Multicellular • Organized multiseriate layers • Cell dimorphism Order Stigonematales Vocabulary prokaryote binary fission thylakoid phycobilins phycobilisome akinete multiseriate trichome false branching nitrogenase eukaryote nucleus chloroplast mitochondrion accessory pigment heterocyst uniseriate sheath true branching photosynthesis Azolla Anabaena Lyngbya Stigonema Who am I? Reading & Viewing Scientific American Extremophiles: http://www.spaceref.com/redirect.html?id=0&url=www.sciam.com/0497issue/0497marrs.html National Geographic: http://www.nationalgeographic.com/world/0010/bacteria/bacteria.html An underworld of hydrogen sulfide harbors life-forms awesome and awful: http://www.nationalgeographic.com/ngm/0105/feature4/index.html NASA interactive page http://nai.arc.nasa.gov/_global/shockwave/g3_matgallery.swf Powers of ten interactive page: http://microscopy.fsu.edu/primer/java/scienceopticsu/powersof10/index.html Mereschowsky, C., (1905). Über Natur und Ursprung der Chromatophoren im Pflanzenreiche., Biol. Centr. 25, 593-604 & 689-691. Mereschowsky, C., (1910). Theorie der zwei Plasmaarten als Grundlage der Symbiogenesis, einer neuen Lehre von der Entstehung der Organismen., Biol. Centr. 30, 353-367, 1910. Margulis, L. (1970). Origin of eukaryotic cells. Yale University Press, New Haven. Picture credits http://www.nhm.uio.no/palmus/galleri/montre/english/gruppe_liste_e.htm http://astrobiology.arc.nasa.gov/roadmap/goals/index.html http://www.lalanet.gr.jp/nsm/E-stromatolite.html http://www.petrifiedseagardens.org/main.htm Saratoga Springs NY http://www.rockhounds.com/grand_hikes/hikes/stromatolites_in_the_hakatai/ http://www.ngdc.noaa.gov/mgg/sepm/palaios/9810/knoll.html
