Transcript The Protists

The Protists
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Eukaryotes.
Most unicellular.
Most aerobic.
Moist environments
Can be photoheterotrophs, photoautotrophs,
chemoheterotrophs or mixotrophs.
• Flagella or cilia.
• All protists can reproduce asexually, some
sexually
Endosymbiosis
• Eukaryotic cells evolved from symbiotic
combinations of prokaryotic cells.
– Mitochondria  aerobic heterotrophic prokaryotic
cells
– Chloroplasts  photosynthetic prokaryotes
Evidence for Endosymbiosis
Similarities between modern bacteria and the
chloroplasts/mitochondria of eukaryotes:
*size
*enzymes
*circular DNA molecules
*process of division
*ribosomes similar
The Candidate Kingdoms
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Archaezoa
Euglenozoa
Alveolata
Stramenopila
Rhodophyta
Green Algae
Candidate Kingdom Archaezoa
• Giardia
• have two nuclei,
flagella, and no
mitochondria
(…parasites)
Candidate Kingdom Euglenozoa
Autotrophic and/or
heterotrophic
flagellates
• Euglena
– 1 or 2 flagella
• Kinetoplasts
parasitic, e.g.
African Sleeping
Sickness (bite of
tsetse fly)
Trypanosoma
Candidate Kingdom Alveolata
• Dinoflagellates, phytoplankton, cause
red tides, color from xanthophyll.
• Apicomplexans, plasmodium, causes
malaria.
• Ciliates, paramecium
Next Group
Dinoflagellates
http://www.microscopy-uk.org.uk/mag/artsep01/dinof.html
http://www.microscopy-uk.org.uk/mag/indexmag.html
Apicomplexans
Leishmania
Parasite infected erythrocyte
Life history of Plasmodium
Ciliates
Stentor
Paramecium
Vorticella
Pseudopod “Protists”
Taxonomic lineage unclear, so no clear
kingdom found… i.e. “misfits”
• Rhizopods, amoebas
• Actinopods, radiolarians
and heliozoans (delicate
silica shells).
• Foraminiferans, marine
with porous calcium shells.
Used as index fossils.
• Slime Molds, cytoplasmic
streaming
Rhizopod
Amoeba
Actinopods
Radiolarians
Foraminiferans
Slime Molds
• Plasmodial Slime Mold – Myxomycota.
Heterotrophic,brightly colored, multinucleated
ameboid mass.
Candidate Kingdom Stramenopila
• Diatoms (bacillariophyta)– unicellular plankton
with box-like silica walls. Diatomaceous earth.
• Golden Algae (chrysophyta) – yellow and brown
carotene and xanthophyll pigments
• Brown Algae (phaeophyta)- largests and most
complex. Seaweeds and kelps, may be as long
as 60m.
• Water Molds (oomycota) – white rusts and
downy mildews
Next Group
Diatoms
Golden Algae - Chrysophyta
Brown Algae - Phaeophyta
Kelp Harvesting
Kelp Structures
• Analogous plant-like structures
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Body = thallus
Root-like structure – holdfast
Stem-like structure – stipe
Leaf-like structure - blades
Water molds, white rusts
and downy mildews
Water mold
White rust on spinach
Candidate Kingdom Rhodophyta
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Red color from pigment
Marine
Multicellular
Carrageenan thickener
Candidate Kingdom Green Algae
*Many scientists advocate inclusion of green algae into
the plant kingdom.
*More than 7000 species, mostly freshwater.
*Unicellular – Chlamydomonas
*Colonial – Volvox
*Multicellular – Ulva
Ulva
Green Algae - Chlorophyta
Volvox
Chlamydomonas
Spirogyra
Chlamydomonas Life Cycle
Ulva Life Cycle