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Cyanobacteria and Algae

Cyanobacteria and Algae

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Cyanobacteria and Algae

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  1. CyanobacteriaandAlgae

  2. Prokaryotes and Eukaryotes

  3. Nutritional Requirements of Prokaryotes • Methods of obtaining carbon • Autotroph (“self-feeding)  incorporate carbon into organic molecules from inorganic sources • Heterotroph (“other feeding”)  derive carbon from breakdown of organic compounds • Methods of deriving energy • Chemotroph (“chemical feeding”)  obtain energy from catalyzing inorganic reactions • Phototroph (“light feeding”)  obtain energy by absorbing light photons

  4. Symbiotic Relationships Between Prokaryotes & Plants • Rhizobium lives in soil • Synthesizes enzyme nitrogenase which converts unusable N2to plant-available ammonium (NH4+) • Forms mutualistic relationship with legumes within root nodules • Plant → carbohydrates & protection • Bacterium → nitrogenase & other enzymes • Both benefit from supply of fixed nitrogen

  5. Cyanobacteria“blue green algae” • Photosynthetic • chlorophyll a, phycobilins • fix nitrogen

  6. Symbiotic Relationships Between Prokaryotes & Plants • Other examples of symbiotic nitrogen fixing Bacteria • Frankia – within cells of root nodules of alders • Anabaena – association with water fern, Azolla • Nostoc – invades cavities in gametophytes of hornworts & cycads

  7. Figure 17.11

  8. Photosynthetic Protists“Algae”

  9. Algae = Photosynthetic Protists • Variety of life histories, body forms, ecological roles • Often named for distinctive colors • Unicellular, colonial, multicellular

  10. Phylum Chlorophyta“green algae” • Unicellular, colonial, multicellular • Most found in freshwater, also some in shallow marine habitats • Pigments: chlorophyll a & b, carotenoid • Food stored as starch • Cellulose cell walls

  11. 50 µm (a) (b) (c) Green Algae

  12. Algal Reproduction • Zygotic • diploid phase of life cycle is single-celled zygote • Examples: Volvox, green algae, Chlamydomonas • Gametic • Multicellular sporophytes • haploid phase of life cycle is single-celled gamete • Examples: some brown algae like Cystoseira • Sporic • multicellular gametophytes & sporophytes • Examples: Ectocarpus, Ulva (isomorphic), Laminaria (heteromorphic)

  13. Zygotic l.h found commonly in green algae Gametic l.h. found in some Brown algae, especially rockweeds (Fucus, Pelvetia, Cystoseira) Sporic l.h. found in kelps, green algae, land plants

  14. Zygotic Life Cycles Chlamydomonas Figure 18.

  15. Ulothrix Life Cycle Figure 18.

  16. Spirogyra Sexual Reproduction

  17. Phylum Chromophyta (Stramenopiles) • All have 2 unequally sized flagella (hairy & smooth) • Photosynthetic ones include: • Chrysophyceae (golden algae) • Bacillariophyceae (diatoms) • Phaeophyceae (brown algae)

  18. 25 µm Figure 28.17 Chrysophyceae“golden algae” • Carotenoid pigments • Usually biflagellated • Most unicellular, some colonial • Cell wall of cellulose

  19. 3 µm Bacillariophyceae“diatoms” • Unicellular algae with silica tests (cell wall) • Important phytoplankton • Contain chl. a & c, fucoxanthin

  20. Reproduction in Diatoms

  21. Blade Stipe Holdfast Phaeophyceae“brown algae” • abundant in cool, shallow marine waters • Largest algae, multicellular thallus • Life history sporic or gametic • More Chlorophylls a & c, fucoxanthin • Carbohydrates can move through sieve elements & be stored (“mannitol”) • Cell wall of cellulose & algin

  22. Gametic(film) Figure 18.

  23. SporicLife Cycle

  24. (b) (c) . Phylum Rhodophyta“red algae” • Widespread • Shallow to deep water • Warm to cool water • Chlorophyl a, phycobilins • complex life cycle involving three types of thallus structures (“triphasic life cycle”) • Cell wall of cellulose, agar or carrageenan

  25. TriphasicLife Cycle Figure 18.

  26. Phylum Euglenophyta“euglena” • “mixotroph”, contains chlorophyll a & b • No cell wall • Contains eyespot • Lack cell wall

  27. Phylum Dinophyta“dinoflagellates” • Unicellular • Contain two flagella. • 1 trails from the cell • 1 encircles the cell • disc-shaped chloroplasts with xanthophyll pigments • Many with tiny projectiles • Many produce toxins (Red Tides)

  28. Dinoflagellates

  29. Ecological & Economic Importance • Phytoplankton • Base of aquatic food chains • Produce about 4x food as earth’s crops • Help build tropical reefs • Coralline green & red algae • Medicine, food, and fertilizer • Uses of algal cell walls • diatomite for filtering, bulking, abrasive • agar as culture medium, gel electrophoresis & in baking • carrageenan used as stabilizer • algin used to absorb water & as additive

  30. Kelp movie