Algae

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Algae

  1. 1. •Algae
  2. 2. Unicellular Green Algae - Chlamydomonas• Chlamydomonas reproduces by binary fission and produces flagellated zoospores for sexual reproduction• Organisms such as Chlamydomonas are believed to be evolutionary ancestors of other species
  3. 3. Kingdom ProtistaThe most ancient eukaryotic kingdomProtists include a variety of eukaryotic forms;they are mostly solitary, some colonial ormulticellular, autotrophic, or heterotrophic andmostly aerobicPerhaps they are best defined as eukaryotes that are NOT fungi, animals, or plants
  4. 4. Classification of algae based on the types of pigmentsTaxonomic Group Photosynthetic Pigments chlorophyll a, chlorophyllCyanobacteria c, phycocyanin, phycoerythrinChloroxybacteria chlorophyll a, chlorophyll bGreen Algae chlorophyll a, chlorophyll b, carotenoids(Chlorophyta)Red Algae chlorophyll a, phycocyanin, phycoerythrin,(Rhodophyta) phycobilins chlorophyll a, chloorphyll c, fucoxanthin andBrown Algae (Phaeophyta) other carotenoidsGolden-brown Algae chlorophyll a, chlorophyll c, fucoxanthin and(Chrysophyta) other carotenoids chlorophyll a, chlorophyll c, peridinin andDinoflagellates (Pyrrhophyta) other carotenoidsVascular Plants chlorophyll a, chlorophyll b, carotenoids
  5. 5. Chlorophyta Green Algae – Forms and examplesA diverse group of fresh water algae but a few are marine formsThe body may be unicellular and motile as in Chlamydomonas orcolonial as in Volvox or filamentous as in Ulothrix and Spirogyra andmay be plant like marine forms as in Fristschiella and UlvaThe cells possess one to many chloroplasts in characteristic shapes indifferent examples. Photosynthetic pigments are chlorophyll a,chlorophyll b, carotenes and xanthophylls
  6. 6. Green Algae - ReproductionVegetative reproduction occurs by cell division, fragmentationand stolon formationAsexual reproduction occurs by the formation of akinites ,zoospores or aplanosporesSexual reproduction involves isogamy or anisogamy or oogamy.Zygote is the only diploid structure in the life cycle. There is aregular alternation of haploid gametophytic and diploidsporophytic generations in the life cycle.• Zoospores: flagellates with eye-spot and contractile vacuole• Aplanospores: non-flagellated cells with contractile vacuole• Autospores: non-flagellated cells lacking contractile vacuole• Terrestrial species predominantly form autospores
  7. 7. Filamentous Green Algae - Spirogyra• Spirogyras are multi-cellular and all the cells of these organisms are haploid andcylindrical in shape• Spirogyra cell wall is surrounded by mucilage• The chloroplast in Spirogyra is wound spirally just inside the cell wall, centralregion of the cell is filled with vacuole, and the nucleus•is suspended by threads of cytoplasm in the cell vacuole
  8. 8. Reproduction in SpirogyraAsexual reproduction in Spirogyra happens via the fragmentation of cells (below left)Sexual reproduction in Spirogyra is of two types, scalariform conjugation and lateral conjugation (below right)
  9. 9. Colonial Green Algae - Volvox
  10. 10. Rhodophyta ( Red Algae) forms• Red algae are multi-cellular aquatic algae which exhibit a highly varied organization of the plant body• Are commonly called red algae due to the presence of a characteristic red pigment called phycoerythrin (red), which masks the color of other pigments like phycocyanin (blue) and chlorophyll (green)• They are generally found attached to rocky stones. Some occur as total or semi parasites on the other algal plants

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