Algae- Plant- like Protists

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Algae- Plant- like Protists

• Textbook 17.4
• pp. 390-394

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Plant like Protists- Algae

• Autotrophs-
• Photosynthetic- chloroplasts-supply O2
• Classified by
• Type of cell wall
• Pigments
• Structure
• Storage carbohydrates
• Reproduce asexually and sexually
• Most are unicellular some are colonial and
  multicellular

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Euglena
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Euglenoids

• Single celled
• Photosynthetic
• One or two flagella
• Lack cell wall
• Live in freshwater
• Example- Euglena- can be both an autotroph and a
  heterotroph.

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B. Dinoflagellates

• Single-celled found in fresh and salt water.
• Cellulose cell wall.
• Two flagella.
• Plankton- surface of ponds, lakes, oceans
• Serve as basis of aquatic food chains.
• Phytoplankton- photosynthetic
• Zooplankton- non-photosynthetic protozoans
• Algae blooms- population explosion due to excess
  nitrates.
• Red tides
• Toxins deadly to fish and humans
• Pfiesteria- bleeding sores in fish neurotoxin
  affects humans
• Bioluminescent- some produce light.

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C. Diatoms

• Single-celled algae found in fresh salt water.
• Glass-like cell wall of silica-
• Many different refractile shapes
• All contain chlorophyll but other pigments
• Many colors of brown or yellow.
• Impt. Food source for marine animals.
• Float near the surface- oil reserves.
• When diatoms die sink and fossil remains-
  diatomaceous earth are mined.
• Uses- grinding/polishing products, filter
  materials, toothpaste.

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D. Seaweeds

• Large multicellular algae
• Not plants- No true roots,stems, or leaves.
• All have chlorophyll.
• 3 groups based on pigments/ color.
• Brown algae- Kelp- biggest- up to 60 m.
• Red algae- tropical- deepest waters 1
  typeagar.
• Green algae- evolutionary ancestor of plants.
• Single- celled- Chlamydomonas with 2 flagella
• Colonial- Volvox ( 100-1000s of cells moving in
  unison)
• Multicellular- filaments- Oedogonium, Spirogyra
• Seaweed Uses-

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Fungus-like Protists

• Textbook 17.3
• pp.387-389

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Fungus-like Protists A. Slime molds

• Not true molds which are fungi
• Decompose dead organic mater
• 2 types
• Plasmodial Slime Molds-
• Cellular Slime Molds

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1. Plasmodial Slime Molds

• Plasmodium- mass of cytoplasm ,no membranes , no
  cell walls, many nuclei.
• Giant supercell ,streaming cytoplasm amoeba
  like.
• Life Cycle-
• Limited resources- reproductive structures-
  fruiting bodies (sporangia) formed.
• Sporangia release haploid spores.
• Better conditions- haploid spores fuse into
  diploid zygote.
• New plasmodium develops.

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2. Cellular Slime Molds

• Unicellular and Multicellular stages
• Individual, colony, and spore stages.
• Asexual and Sexual reproduction.
• Scarce food- cells stick together
• Slug-like colony
• Trail of slime

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B. Water molds- Oomycota

• Freshwater.
• Decomposed dead plants,animals.
• Parasitic forms- skin or gills of fish.
• Unicellular or multicellular
• Sexual reproduction- egg cell

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Downy molds

• Reproduce sexually- egg cell
• Spores- wind blown
• Plant parasites
• Irish potato famine mid 1800s
• Example of effects of clones
• Lack of genetic variation
• Water and Downy molds-
• DNA studies
• More closely related to plant-like protists
  (algae)

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Evolution

• Textbook 17.5
• pp. 395-397

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Evolution hypothesis

• Protists evolved from ancient prokaryotes
• Animals, Plants, and Fungi evolved from
  animal-like, plant-like, and fungus-like protists
• 2 main processes-explain complex eukaryotic cell.
• Infolding
• Endosymbiosis

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Infolding

• Inward folding of cell membrane of bacterial
  cells
• Produced internal membranes of eukaryotic cells
• nuclear membrane, endoplasmic reticulum, golgi
  apparatus.
• Eukaryotic Cell- separate compartments for
  chemical reactions.