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The Protists
Protists are Eukaryotic
*and most Eukaryotes are Protists!
Reminder: Eukaryotes have a nucleus and other membrane-bound organelles, such as mitochondria and chloroplasts
Copyright © 2004 by Pearson Education, Inc.
*Protista is an informal term to refer to the eukaryotes that do not belong in the Animalia, Plantae, or Fungi kingdoms
*A very diverse group, some have traits similar to those of animals, while some are like plants and others are like fungi. And some are like all three!
*Most are unicellular but some are multicellular (like some algaes)
*Lack specialized tissues that would group them within the animal, plant, or fungi kingdoms
*Example: algae lack the vascular tissues characteristic of the plants
*Found everywhere there is water
Keep in mind, the large multicellular organisms that we know best (plants, animals, and fungi) are the tips of just a few
branches on the great tree of life
Barton, et al., Evolution, Cold Spring Harbor Laboratory Press, 2007
Eukaryotes are divided into 5 supergroups
Campbell, et al., Biology, Pearson, 2008
Supergroup Excavata
*Some have an ‘excavated’ groove on one side of the cell body
*Excavates include protists with modified mitochondria and others with unique flagella
*Three main groups:
*Diplomonads
*Parabasalids
*Euglenozoans
Supergroup Excavata
Diplomonads*Lack plastids (organelle
that makes chemical compounds)
*Have mitosomes (reduced mitochondria)
*Have two nuclei and multiple flagella
*Most found in anaerobic environments
*Many are parasites
*Giardia intestinalis
Campbell, et al., Biology, Pearson, 2008
*Also have reduced mitochondria called hydrogenosomes (hydrogen gas as a byproduct)
*Also lack plastids
*Most found in anaerobic environments
*Trichonmonas vaginalis
Supergroup Excavata
Parabasalids
*Very diverse group that includes heterotrpohs, photosynthetic autotrophs, and parasites
*All have a spiral or crystalline rod inside the flagella (unknown function)
Supergroup Excavata
EuglenozoansCampbell, et al., Biology, Pearson, 2008
*Kinetoplastids
*Single large mitochondrion containing an organized mass of DNA called a kinetoplast
*Trypanosoma sp.
Supergroup Excavata
EuglenozoansThe Parasite Museum, www.parasitemuseum.com, 2011
*Brain-Eating Amoebas!!!
* Not really an Amoeba, it’s an Amoeba-flagellate
* Naegleria fowleri
* Lives in warm freshwaters but has also been found in soil and low-chlorinated pools
* Invades the central nervous system via the nose where it does extensive damage
* It then travels up nerve fibers into the brain where it begins to eat the brain piece by piece
* Survival is less than 1%
* 1937-2007: 121 deaths in U.S
* 2007: 12 year-old boy and 22 year-old man die at Lake LBJ
* 2010: 7 year-old boy dies near Glen Rose (10th case in Texas since 2000)
Supergroup Excavata
Euglenozoans
http://animal.discovery.com/videos/monsters-inside-me-the-brain-eating-amoeba.html
http://www.dpd.cdc.gov, 2011
*Euglenids
*Have a pocket at one end of the cell from which two flagella emerge
*Many are ‘mixotrophs’ in that they can swith from autotrophic to heterotrophic to adapt to changes in their environment
*Euglena sp.
Supergroup Excavata
Euglenozoanswww.noaa.gov, 2011
*Large, extremely diverse group of protists
*Includes some of the most important photosynthetic organisms on Earth as well as some very well known pathogens
*Two main groups:
*Alveolates
*Stramenopiles
Supergroup Chromalveolates
*Alveolates
*Have membrane-bounded sacs (alveoli) just under the plasma membrane (unknown function)
*Includes three subgroups:
*Dinoflagellates
*Apicomplexans
*Ciliates
Supergroup Chromalveolates
AlveolatesMona Hoppenrath, http://tolweb.org, 2011
*Dinoflagellates
*Cells reinforced by cellulose plates
*Two flagella located in perpendicular grooves
*Greek dinos= whirling
*Abundant components of both marine and freshwater plankton
Supergroup Chromalveolates
Alveolates
Dave Hill, www.botany.unimelb.edu.au, 2011
*Dinoflagellates
*Red tide: dinoflagellate bloom caused by high nutrients
*Toxins produced by some have caused massive kills of invertebrates and fishes
Supergroup Chromalveolates
Alveolates
www.oddee.com, 2011
*Dinoflagellates
*Zooxanthellae
*Live in a symbiotic relationship with organisms like coral
*Photosynthetic autotrophs that provide the host with sugars
Supergroup Chromalveolates
Alveolates
Scott R. Santos, Auburn University
*Dinoflagellates
*Zooxanthellae
Supergroup Chromalveolates
Alveolates
Eric Yao, 2011
*Apicomplexans
*Nearly all are parasites
*Most have intricate life cycles requiring two or more host species
*Plasmodium sp. (malaria)
Supergroup Chromalveolates
Alveolates
The American Society for Clinical Investigation, 2011
*Ciliates
*Large, varied group
*Use cilia to move and feed
*Have two types of nuclei: tiny micronuclei and large macronuclei
*Usually reproduce asexually by binary fission
*Very common in freshwater, some in saltwater
*Paramecium sp.
Supergroup Chromalveolates
Alveolates
Power And Syred / Science Photo Library, 2011
*Stramenopiles
*Group of marine algae
*Characteristic flagellum has numerous fine, hairlike projections
*Usually paired with a shorter, smooth flagellum
*Four groups:
*Diatoms
*Golden algae
* Brown algae
*Oomycetes
Supergroup Chromalveolates
Stramenopiles
Power And Syred / www.jochemnet.de, 2011
*Diatoms
*Unicellular algae
*Unique glass-like wall made of silica
*Major component of freshwater and marine plankton
*Massive accumulations of fossilized diatoms make diatomaceous earth
Supergroup Chromalveolates
Stramenopiles
Wikimedia commons, 2009
*Golden Algae
*Golden because they have yellow and brown pigments
*Most unicellular, some colonial
*Typically biflagellated
*Component of freshwater and marine plankton
Supergroup Chromalveolates
Stramenopiles
2006 Olympus BioScapes Digital Imaging Competition, www.scientificamerican.com, 2011
*Brown Algae
*Largest and most complex of the algae
*Multicellular
*Most marine
*Common in cooler water
*A ‘seaweed’
*Kombu used in japanese soups
*Algin, substance from the cell wall, is used to thicken many processed foods: pudding, ice cream, salad dressing, etc.
Supergroup Chromalveolates
Stramenopiles
*Brown Algae
*Thallus:algae body that is plant-like
*Stipe: like a stem but no vascular tissue
*Holdfast: like roots but just an anchor
*Blade:like leaves but without vascular tissues
Supergroup Chromalveolates
Stramenopiles
Campbell, et al., Biology, Pearson, 2008
*Oomycetes
*Water molds
*Used to be classified as fungi
*Oomycete= ‘egg fungus’
*Many have filaments that resemble fungal hyphae
*Cell walls made of cellulose
*Decomposers or parasites
Supergroup Chromalveolates
Stramenopiles
*Supergroup Rhizaria
*Grouped based on molecular similarities not morphology (form and structures)
*All have Pseudopodia: extensions that bulge from cell surface
*Includes 3 groups:
*Forams
*Radiolarians
*Chlorarachniophytes
Supergroup Rhizaria
*Foraminiferans (Forams)
*Latin
* foramen: little hole
*Tests: porus shell made of calcium carbonate
*Pseudopodia extend through the pores function in feeding, test formation, and feeding
*Most photoautotrophic (symbiotic zooxanthellae)
*Most are benthic but some planktonic
Supergroup RhizariaForams