(Source of page: Dr. Nilsson's old lecture notes. Permission given in 2001 by McGraw-Hills then sales representative, Don Grainger, to use the picture online on lecture notes.)
Several illustrations of tissues from S. S. Mader. 2001. Biology. McGraw-Hill.
Introduction pages of texts used...
--- General Characteristics ---
Kingdom of the Crossroads. The lumping kingdom. The Protista is a diverse group of unicellular and multicellular eukaryotic organisms that inhabit aquatic or moist habitats. Over 65,000 species of protistans have been identified, and the relationships between these organisms are constantly being revised and updated. It is difficult to come up with general characteristics for the group.
1. eukaryotic
2. aerobic
3. some are unicellular, some are multicellular
4. some have cell wall, some do not have cell wall
5. some are autotrophic, some are heterotrophic
6. some are small, some are large (larger than bacteria)
Until the classification can be clarified (probably with help of DNA analysis):
Cell Organization.
Most protista are unicellular. As a group they are considered to be the simplest of the eukaryotic kingdoms (in the Domain Eukarya).
-- However, at the cellular level many protista are extremely elaborate and complex.
(Each unicellular protista is not like a single cell of a human or another multicellular organisms, but is itself a complete organism, as any plant or animal.)
Endosymbiotic theory (see below): Eukaryotic cells evolved from large prokaryotic cells that engulfed once free-living bacteria -- now mitochondria and chloroplasts.
Reproduction and Life Cycles.The Protista have very different reproduction methods and life cycles:
i. Diplontic: life cycle & reproduction like animals
- diploid multicellular stage (only the gametes formed after meiosis are haploid) - Diploid stage: the zygote + the adult
- Haploid stage: the gametes
ii. Alternation of generations: life cycle & reproduction like plants
- both diploid (sporophyte) and haploid (gametophyte) multicellular stages - Diploid stage: the zygote + the sporophyte adult
- Haploid stage: the gametes + the gametophyte adult + the spores
iii. Haplontic: life cycle & reproduction like fungi
- haploid multicellular stage (only the zygote, formed after fertilization, is diploid) - Diploid stage: the zygote
- Haploid stage: the gametes + the adult
Habitat. The Protista are found almost anywhere there is water.
def. motile: Moving or having the power to move. . [Compare w. "sessile".]
def. sessile: Permanently anchored (e.g., to rocks, logs, or coral), not having the power to move. . [Compare w. "motile".]
def. plankton: Organisms (usually microscopic) floating or weakly swimming in freshwater or saltwater, carried by currents. (There are two forms: zooplankton [animal-like] and phytoplankton [plant-like].)
i. oceans
ii. ponds
iii. lakes
iv. rivers
v. damp soil
vi. leaf litter
vii. other terrestrial habitats with moisture
def. plankton: Organisms (usually microscopic) floating or weakly swimming in freshwater or saltwater, carried by currents. (There are two forms: zooplankton [animal-like] and phytoplankton [plant-like].)
Ecologically important. The Protista are important organisms in plankton communities.
i. First link in marine and freshwater food webs.
ii. Major oxygen producers on this planet:
50% phytoplankton in the oceans
50% land plants (40% from the tropical rainforests)
--- Endosymbiotic Theory ---
Evolution of the Eukaryotic cell -- Margulis Endosymbiotic Theory
--- Classification ---
Laboratory specimens
As already stated, the Protista is a diverse group of unicellular and multicellular eukaryotic organisms, and the relationships between these organisms are constantly being revised and updated. We are here following the old traditional classification dividing the kingdom into three groups, plantlike, moldlike, and animallike protistans.
• Green color -- Chlorophyll (green pigment) -- Photosynthesizing organisms (autotrophs). Algae is a term used for a large group of photosynthetic protistans, many are planktons (phytoplanktons). • Can use energy from the sun directly: Autotrophs -- self-feeders
def. Autotrophs: organisms capable of producing their own food from inorganic materials & sunlight (or another environmental energy source).
def. Photosynthesis: the conversion of light energy to chemical energy (stored in glucose produced) from carbon dioxide and water.
sunlight + 6CO2 + 6H2O >>> C6H12O6 + 6O2
Phylum Chrysophyta (Diatoms)
• Unicellular, golden, brownish color, plankton Have chlorophyll, but masked by other pigments (not green). Economic importance: Have a shell which the industry use to make abrasive materials or filter materials.
Phylum Pyrrhophyta (Dinoflagella)
• Unicellular, often red color, plankton. Cause Red tides, and Fish Death ("The Cell from Hell").
Gonyaulax, Gymnodinium, "Red Tides"
When present in large numbers, are capable of producing toxins that harm other organisms, including humans.
Pfiesteriapiscicida, "the Cell from Hell"
Have chlorophyll, but masked by other pigments (usually not green). Have flagella in grooves. def. red tide: A population explosion or bloom of microscopic protista, called dinoflagellates, containing toxins that can poison marine life.
Phylum Euglenophyta (Euglenozoa)
• Unicellular, green color, motile
Free-living, both heterothoph and autotroph (animal or plant?) • Euglena
• Unicellular or multicellular green color, (unicellular usually motile). Economic importance: Some sold dry in health food stores. The closest relatives to the plants! • Volvox, • Spirogyra, • Ulva (sea lettuce)
Phylum Phaeophyta (Brown Algae)
• Multicellular, brown color, sessile Have chlorophyll, but masked by brown pigments (phycobilins). Economic importance: used as thickening agent in food.
Have chlorophyll, but masked by red pigments (xanthophylls) which can trap sunlight in deep marine waters! Economic importance: Some sold dry in health food stores, some used for agar (used in microbiology as growth medium for bacteria, and as ice cream stabilizer) • Chondrus (Irish moss)
• Mold-like protistans (Water and Slime Molds)
• Natural color NOT green -- no chlorophyll -- do not photosynthesize (heterotrophs) Phylum Oomycota (Water Molds)
• Free-living, or parasite on plants -- Cause Irish Potato Blight. Sessile.
Some parasitic on aquarium fish!
The blight was the fungus Phytophthora infestans which destroyed potato plants and was the principal cause of what came to be known as the Irish Potato Famine. The blight wiped out the potato crop in 1845, 1846 and again in 1848. People were left with nothing to eat and no way to make money to support themselves. Many wandered the countryside, begging for food or work. Others ate grass and weeds to survive. Those who could afford to, left the country in search of a better life. Canada's Digital Collections (http://collections.ic.gc.ca/potato/history/ireland.asp)
Phylum Myxomycota (Slime Molds; Gymnomycota)
• Free-living. Motile (often as "steaming" gel masses) Amoeba-like, slimy masses that can migrate to find food!
• Animal-like protistans (Protozoa) • Natural color NOT green -- no chlorophyll -- do not photosynthesize (heterotrophs)
• Cannot use the sun directly -- must feed on something: Heterotrophs
def. Heterotrophs: organisms incapable of producing their own food, and therefore depend directly or indirectly on producers to meet their food requirements.
def. parasitism: Ecological relationship between two organisms where only one organism benefits, by deriving nourishment from the other, without killing it (at least not immediately) but usually doing harm to it.
def. mutualism: Ecological relationship between two organisms where both organisms benefit.
Phylum Sarcodina (Rhizopoda; Amoebozoa) • Amoeba • Free-living, or parasite. May cause disease. Motile. Characteristic of this group: pseudopodia -- cytoplasmic extensions of the cell body.
Phylum Ciliophora (Ciliates)
• Paramecium • Free-living, ciliated protozoa. In ponds, do not cause disease. Motile.
Characteristic of this group: cilia -- numerous hairlike structures that beat in synchrony on the cell surface.
Phylum Sporozoa (Apicomplexa)
• Plasmodium
• Parasite -- cause Malaria (fever). Motile Characteristic of this group: all parasitic -- must live inside of cells part of their life. Malaria: serious world wide disease! 150 - 300 million new cases per year. Transmitted by a mosquito (Anopheles)
Phylum Zoomastigophora (Parabasalida)
• Parasites. Motile Characteristic of this group: flagella -- few tail-like structures on the cell surface.
• Trypanosoma
a. Sleeping sickness in Africa (Trypanosomagambiense. Cause coma. Transmitted by the tse-tse fly (Glossina) (many areas in Africa uninhabitable.)
b. Chaga's disease in South and Central America (Trypanosomacruzi. Cause heart disease, enlarged intestines, CNS.) Transmitted by the Kissing Bug [family Reduviidae]
• Giardia -- hiker’s diarrhea
• Trichomonas -- Trichomoniasis (STD of urinary and reproductive organs).
(Source: Dr. Nilsson's old lecture notes. Permission given in 2001 by McGraw-Hills then sales representative, Don Grainger, to use the picture online on lecture notes.)
Ch. 17.
Ch. 22
Ch. 29
Introduction pages of texts used... 
General Characteristics ---
Plant-like protistans (Algae)
Mold-like protistans (Water and Slime Molds)
Animal-like protistans (Protozoa)
50% phytoplankton in the oceans
Endosymbiotic Theory ---
Classification ---
Phylum Phaeophyta (Brown Algae)
Phylum Rhodophyta (Red Algae)
