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