Features of Kingdom Protista

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Features of Kingdom Protista

• All members have eukaryotic cells.
• Individual life cycles vary considerably, but
  reproduction is generally by cell division and
  sexual processes.
• Most multicellular members produce some motile
  cells.

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Outline

• Phylum Chlorophyta
• Phylum Chromophyta
• Phylum Rhodophyta
• Phylum Euglenophyta
• Phylum Dinophyta
• Phylum Cryptophyta
• Phylum Prymnesiophyta
• Phylum Charophyta
• Phylum Myxomycota
• Phylum Dictyosteliomycota
• Phylum Oomycota

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Phylum Chlorophyta

• The Green Algae
• Includes about 7,500 species that occur in a rich
  variety of forms and occur in diverse, widespread
  habitats.
• Greatest variety found in freshwater lakes,
  ponds, and streams.
• Most have a single nucleus.
• Most reproduce both sexually and asexually.

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Fig. 18.2
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Green Algae

• contain pigments (chl a b) similar to higher
  plants.
• store food in the form of starch within their
  chloroplasts.

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Phylum Chlorophyta

• Chlamydomonas
• Common inhabitant of freshwater pools.
• Pair of whip-like flagella on one end pull the
  cell through the water.
• Single, cup-shaped chloroplast with one or two
  pyrenoids inside.
• Pyrenoids Proteinaceous structures thought to
  contain starch synthesis enzymes.

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Chlamydomonas
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Chlamydomonas

• Asexual Reproduction
• Nucleus divides by mitosis, and cell contents
  become two daughter cells within the cellulose
  wall.
• Develop flagella and swim away.

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Sexual Life Cycle of Chlamydomonas
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Phylum Chlorophyta

• Ulothrix
• Thread-like alga.
• Single row of cylindrical cells forming a
  filament.
• Basal cell functions as a holdfast.

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Ulothrix Life Cycle
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Phylum Chlorophyta

• Spirogyra (Watersilk)
• Common freshwater algae consisting of unbranched
  filaments of cylindrical cells.
• Frequently float in masses at the surface of
  quiet waters.
• Asexual Reproduction
• Fragmentation of existing filaments.
• Sexual Reproduction
• Papillae fuse and form conjugation tubes.

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Spirogyra Sexual Reproduction
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Phylum Chlorophyta

• Oedogonium
• Epiphytic filamentous green alga.
• Each cell contains a large, netlike chloroplast
  that rolls and forms a tube around and toward the
  periphery of each protoplast.

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Phylum Chlorophyta

• Other Green Algae
• Chorella - Widespread green alga composed of tiny
  spherical cells.
• Reproduce by forming either daughter cells or
  autospores through mitosis.
• Desmids - Mostly free-floating and unicellular.
• Reproduce by conjugation.

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Fig. 18.8
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Phylum Chlorophyta

• Other Green Algae
• Hydrodictyon (Water Nets) - Net-like, tubular
  colonies with hexagonal or polygonal meshes.
• Asexual reproduction as well as isogamous sexual
  reproduction.
• Volvox - Colonial green algae held together in a
  secretion of gelatinous material
• Reproduction asexual or sexual.

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Fig. 18.9
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Fig. 18.10
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Phylum Chlorophyta

• Other Green Algae
• Ulva (Sea Lettuce) - Multicellular seaweed with
  flattened green blades.
• Isomorphic reproductive structures.
• Cladophora - Branched, filamentous green alga
  with species represented in both fresh and marine
  waters.
• Mostly multinucleate.

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Fig. 18.11
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Phylum Chromophyta

• The Diatoms (Bacillariophyceae)
• Among best known and economically most important
  members of this phylum.
• Mostly unicellular
• Occur in both fresh and salt water.
• Particularly abundant in colder marine habitats.

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Fig. 18.14
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Reproduction in Diatoms
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Phylum Chromophyta

• The Brown Algae (Phaeophyceae)
• Relatively Large
• Most Marine
• Non-Unicellular or Colonial
• Many have a thallus differentiated into a
  holdfast, a stipe, and blades.
• Blades may have gas-filled bladders.
• Sargassum - Floating Brown Seaweed
• Fucus - Common Rockweed

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Brown Alga Nereocystis
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Fig. 18.16
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Fig. 18.18
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Phylum Rhodophyta

• The Red Algae
• Most species are seaweed.
• Tend to occur in warmer and deeper waters than
  brown algae.
• Most are filamentous.
• Relatively complex life cycle involving three
  types of thallus structures.
• Colors mostly due to phycobilins.
• Numbers of species produce agar.

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Fig. 18.21
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Phylum Euglenophyta

• The Euglenoids
• Spindle-shaped.
• No cell wall, thus changes shape as it moves.
• Sub-membrane strips and membrane form pellicle.
• Contains gullet.
• Contains red eyespot.
• Reproduction by cell division.

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Fig. 18.23
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Phylum Dinophyta

• The Dinoflagellates
• Unicellular
• Contain two flagella.
• One trails behind the cell.
• Other encircles the cell at right angles.
• Most have disc-shaped chloroplasts.
• Contain xanthophyll pigments.
• Many have tiny projectiles.
• Many types of toxins produced. (Red Tides)

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Dinoflagellates
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Human and Ecological Relevance of Algae

• Diatoms
• Oils are sources of vitamins.
• Diatomaceous Earth
• Filtration
• Polishes
• Reflectorized Paint
• Other Algae
• Chlorella
• Potential human food source.

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Human and Ecological Relevance Algae

• Algin
• Produced by giant kelp.
• Ice Cream, Salad Dressing
• Latex Paint, Textiles, Ceramics
• Agar
• Produced by red alga Gelidium.
• Solidifier of nutrient culture media for growth
  of bacteria.

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Table 18.2
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Phylum Myxomycota

• The Plasmodial Slime Molds
• Totally without chlorophyll and are incapable of
  producing their own food.
• Distinctly animal-like during much of life cycle,
  but fungus-like during reproduction.
• Plasmodium converts into separate small sporangia
  (each containing spores) during times of
  significant environmental changes.

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Fig. 18.30
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Fig. 18.31
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Phylum Dictyosteliomycota

• The Cellular Slime Molds
• About two dozen species of cellular slime molds
  are not closely related to the other slime molds.
• Individual amoebalike cells feed independently,
  dividing and producing separate new cells
  periodically.
• Human and Ecological Relevance
• Break down organic particles to simpler
  substances.

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Fig. 18.33
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Phylum Oomycota

• The Water Molds
• Often found on dead insects.
• Range in form from single spherical cells to
  branching, threadlike, coenocytic hyphae.
• Coenocytic hyphae may form large thread masses
  (mycelia).

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