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Protists

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Based on what the organism is not!!! If you are eukaryotic and not a fungus, plant or animal ... Contractile vacuole (osmosis) Gullet, anal pore, trichocysts ... – PowerPoint PPT presentation

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Title: Protists


1
Protists
2
What is a protist?
  • All (some say the first) eukaryotes
  • They are a very diverse group
  • Most are unicellular
  • Many are multicellular
  • Many are microscopic
  • A single cell can be 1 meter long
  • Autotrophs and heterotrophs
  • Sexual and asexual reproduction

3
Classification
  • Based on what the organism is not!!!
  • If you are eukaryotic and not a fungus, plant or
    animal
  • Then you are a protist
  • Active field of systematics, cladistics and
    taxonomy

4
Evolution again
  • Evolution of eukaryotes
  • Appearance of internal membranes
  • Appearance of symbiosis (mutualism)
  • Re-read section 3-4

5
Evolution of sexual reproduction
  • Chromosome shuffling during meiosis
  • Crossing over during meiosis
  • Leads to increase in genetic variation
  • Remember all this???

6
Autotrophic Protists
  • Algae
  • Perform 40 of the photosynthesis on earth
  • Red algae, green algae, brown algae
  • More later in Chapter 24

7
Heterotrophic Protists
  • Commonly called protozoans
  • Most are uniclellular
  • Can be predators, decomposers or parasites

8
Four Phyla of Protozoans
  • Based on how they move
  • Use flagella (Flagellates, Zoomastigina)
  • Example Trichonympha in Termite gut
  • Example Typanosoma causes African sleeping
    sickness
  • Illustration on page 536

9
Four Phyla of Protozoans
  • Based on how they move
  • Use pseudopods, false feet (Sarcodines,
    Sarcodina)
  • Example Ameba
  • Example Forams (Foraminifera)
  • Illustration on page 537

10
Four Phyla of Protozoans
  • Based on how they move
  • Use cilia short hairs (Ciliates, Ciliophora)
  • Example Paramecium
  • Ciliates have
  • Micronucleus and macronucleus
  • Contractile vacuole (osmosis)
  • Gullet, anal pore, trichocysts
  • Binary fission normally, conjugation when
    stressed
  • Illustration on page 538

11
Four Phyla of Protozoans
  • Based on how they move
  • Use nothing, i.e., dont move (Sporozoans,
    Sporozoa)
  • Example Plasmodium
  • Causes malaria, uses two hosts
  • Mosquitoes and birds or mammals

12
Fungus-like Protists
  • Slime molds
  • Life mostly as solitary creatures, looks
    ameba-like
  • In stress attracts others to form a giant mass
  • Produces fruiting body cells
  • Produces spores and disperse the spores in the
    wind

13
Protist Reproduction
  • No generic life cycles
  • Most use sexual reproductive strategies
  • Algae show alternation of generations
  • One generation is diploid (sporophyte)
  • Next generation is haploid (gametophyte)
  • Next generation is diploid and so on
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