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					Eukaryotes
  Protista
    What do Eukaryotes have that
        Prokaryotes do not?
 Membrane-bound nucleus
 Mitochondria, chloroplasts, and
  endomembrane system
 Cytoskeleton

 Flagella of microtubule construction

 Multiple chromosomes of linear DNA
  compactly arranged with proteins
 Diploid life stages

 Mitosis and Meiosis and Sex
Compartmentalization of
      functions
 occurs in eukaryotes
Endosymbiotic theory of eukaryotic
           evolution
   Evidence of mitochondria and chloroplast
    origin
    – Appropriate size
    – Replication by binary fission
    – Inner membranes containing enzymes and
      transport systems similar to prokaryotic
      plasma membranes
    – DNA is circular and not complexed with
      histones
    – Have their own ribosomes, tRNAs and other
      components for transcription/translation
    – Ribosomes are more similar to prok. than euk.
A model of the origin of eukaryotes
Protistan taxonomy is in a
  state of flux (a mess)
  Your Lab book and your text
    book approach protists in
  very different manners using
      different terminology.
   Your lab book is the more
 “classic” approach and we will
     follow that more closely
Traditional hypothesis for how the three domains of life are related
An alternative hypothesis for how the three domains of life are related
A tentative phylogeny of eukaryotes (Campbell 6th Edition)




                                                             We are going
                                                             to look at
                                                             protists using
                                                             a more
                                                             „Classic”,
                                                             simpler
                                                             scheme
     First a couple definitions
 Plankton
  – Communities of organisms, mostly
    microscopic, that drift passively or swim
    weakly near the surface of oceans,
    ponds, and lakes
 Encystment
  – Cyst formation
  – A response to adverse conditions
  – Allows a parasitic species to survive
    outside a host, allows others to survive
    hostile environmental conditions
  – Only some protists can do this
         Archezoans
Lack mitochondria or
 chloroplasts
Have prokaryotic-like
 ribosomes
Simple cytoskeletons
                   Archezoans
Giardia
 lamblia
Unicellular
  flagellate.
  Most
  commonly
  transmitted in
  the cyst form
  through water
  contaminated
  with human
  feces
Trichomonas vaginalis             An inhabitant
of vaginal tract of human females. Can be
sexually transmitted. Has flagella and an
undulating membrane for movement
         The Protozoa
          (animal-like protists)
 Diverse group of heterotrophic
  protists

           grouped into different
 Classically
 Phyla based upon their
 movement and how they feed
             The Protozoa
         Rhizopoda – the amoebas
 Very  simple
  protists,
  unicellular
 Pseudopodia

 Entamoeba
  histolytica
  – ( human pathogen)
Amoeba proteus
Use of pseudopodia for feeding
             The Protozoa
Actinopoda – (Helizoans and Radiozoans)
 Axopodia   = projections reinforced
    by bundles of microtubules thinly
    covered by cytoplasm

 Most    are planktonic

   Heliozoans – fresh water

   Radiozoans- marine, silica shells
Actinopods: Heliozoan (left), radiolarian (right)
Radiolarian skeleton
          The Protozoa
         Foraminifera (Forams)
 Marine organisms
 Porous shells of
  organic material
  hardened by
  calcium carbonate
 Many have algae
  living beneath the
  shell which provide
  nutrients via
  photosynthesis
Foraminiferan
                The Protozoa
         Apicomplexa (Sporozoans)
 All species are obligate intracellular
  parasites of animals
 Toxoplasma gondii
    – Toxoplasmosis
   Cryptosporidium
    – Diarrhea. Transmitted via fecal contamination
    – Water supply outbreaks have been reported
   Plasmodium
    – Malaria
The two-host life history of Plasmodium, the apicomplexan that causes malaria
             The Protozoa
       Zoomastigophora (flagellates)
 Move by whip-like flagella
 Trichonympha
    – Inhabits the gut of termites
   Trypanosoma
    – Hemoflagellate
    – African Sleeping sickness
Trichonympha
Trypanosoma, the kinetoplastid that causes sleeping sickness
           The Protozoa
           Ciliophora (ciliates)
                                Stentor   Paramecium
 Move by cilia
 Most are free-living
  in fresh water
 Paramecium

 Stentor

 Vorticella




                   Vorticella
Ciliates: Paramecium
       Fungus-like Protists
 Filamentous  body structure at times
  makes them appear to be like molds,
  but they are more closely related to
  amoebas than to true fungi.
 Myxomycota (plasmodial slime molds)

 Acrasiomycota (cellular slime molds)

 Oomycota (water molds, white rusts,
  downy mildews)
The life cycle of a plasmodial slime mold, such as Physarum
Plasmodial slime mold
Slime mold Sporangia
The life cycle of a cellular slime mold (Dictyostelium)
Dictyostelium life cycle
Stages of Dictyostelium
The life cycle of a water mold (Layer 3)
Water mold: Oogonium
Powdery mildew
                Algae
 Diverse group of photoautotrophic
  aquatic organisms
 Major role in aquatic food chains

 Fix carbon dioxide into organ carbon

 Produce somewhere between 50%
  and 80 % of the Earth‟s oxygen
                       Algae
   Dinoflagellata (dinoflagellates)
– They have two flagella and may have armor
  (cellulose plates) or may be naked (without
  armor). Dinoflagellates have pigments and
  can carry on photosynthesis. Major
  component of phytoplankton.
– Gonyaulax
    Red tide
    Paralytic shellfish poisoning

– Peridinium (lab)
– Noctiluca miliaris
    Bioluminescent
Dinoflagellate
Dinoflagellates
Swimming with bioluminescent dinoflagellates
         Algae
Bacillariophyta (Diatoms)
a diatom, a unicellular "alga"
Chrysophyta
Golden algae
   Phaeophyta (Brown algae)
 Largest   and most complex of the
  algae
 Kelp is a brown algae
  – Giant kelp - up to 100 meters in size
 Seaweeds = large, multicellular
 marine algae of coastal waters which
 include members of the Brown, Red,
 and Green algae groups
Australian bull kelp (Durvillea potatorum)
Kelp forest
Kelp forest
  Red algae: Dulse (top), Bonnemaisonia hamifera (bottom)




Rhodophyta


Red Algae
      Chlorophyta (green algae)
   Over 7000 species known
    – Freshwater and marine
    – Unicellular and multicellular forms
 Chlamydomonas
 Volvox

 Spirogyra

 Cladophora

 Lichens=a mutualistic relationship
  between a green algae and a fungus
Colonial and multicellular chlorophytes: Volvox (left), Caulerpa (right)
Chlamydomonas
Volvox
Spirogyra
Chladophora
Lichens

				
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posted:11/11/2011
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