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What are PROKARYOTES? They are ancient life forms known as bacteria • No true nucleus • No chloroplasts • No mitochondria other organelles Two major classes of bacteria Archaebacteria Methanogens Extreme Thermophiles Extreme Halophiles TEM of dividing cell & Eubacteria Cyanobacteria (Blue-green algae) Gram negative bacteria Gram positive bacteria & other THE FOLLOWING ARE DIVISION ◦ CYANOPHYTA-Blue green algae Some Characteristics of the Cyanobacteria * Contain Chlorophyll a and carotenoids, plus the phycobilins (proteinaceous photosynthetic pigments) phycocyanin and phycoerythrin (c f. Rhodophyta), found in thylakoids * Have cell walls of peptidoglycan, often with a mucilaginous sheath * The carbohydrate stored is glycogen * No flagella, but some exhibit gliding movements * Some fix nitrogen in specialized cells In some genera the mucilaginous sheath forms a gelatinous matrix Gelatino us matrix Individua l cells Gloeocapsa Filaments of Nostoc commune forming a gelatinous ball 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 Ancient organisms but well suited to earth’s habitats 2000 species, 150 genera Habitats: virtually everywhere Oceans Freshwater Soil Hotsprings Epiphytes 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 CLASS-CYANOPHYCEAE ORDER-CHROOCOCCALES Gloeocapsa Merismopedia microcystis ORDER-OSCILATORIALES Oscilatoria Lyngbya Nostoc Anabaena Diversity Order Chroococcales Microcystis Merismopedia 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 Akinete Anabaena Order Nostocales Cool stuff Order Nostocales