1. Protists

2. What is a Protist? •Eukaryotic
•Unicellular & some multicellular & some colonial
•Heterotrophic or autotrophic
•Animal-like protist (protozoa)
• unicellular & heterotrophic
• motile
•Plant-like protist (includes algaes)
• most unicellular & photosynthetic
•Fungus-like protist
• heterotrophic with fungal characteristics

3. Protist Evolution Protists first appeared 1.5 billion years ago.
Biologist Lynn Margulis has hypothesized that the first
eukaryotes evolved from a symbiosis of several cells.
Mitochondria & chloroplasts
found in eukaryotic cells
may be descended
From aerobic &
photosynthetic
prokaryotes that
began to live
inside larger cells.

4. Animal-like Protists: Protozoans
Phylum Zoomastigina (zooflagellates)
Most possess one or two flagella (some with thousands)
Ex: Trichomonas & Trichonympha

5. Animal-like Protists: Protozoans
Phylum Sarcodina (sarcodines)
•Use pseudopods (false-feet) for feeding & movement
•Some produce elaborate shells that contains silica or calcium carbonate
•Some involved in formation of sedimentary rock
•Most free living, but a few are parasitic
• Ex: Amoeba & foraminiferans

6. Animal-like Protists: Protozoans
Phylum Sarcodina (sarcodines) – the Ameoba

7. Animal-like Protists: Protozoans
Phylum Sarcodina (sarcodines) – the Ameoba

8. Animal-like Protists: Protozoans
Phylum Ciliophora (ciliates)
•All have cilia & most use cilia
for movement
•Contain two nuclei:
• Macronuclei – contains working copies of genetic
information
• Micronuclei – contains a “reserve copy” of genes
•Sexual reproduction via conjugation
•Some use trichocysts (stiff projections) for defense
• Ex: Paramecium, Stentor & Didinium

9. Animal-like Protists: Protozoans
Phylum Ciliophora (ciliates) – the Paramecium
Contractile vacuoles
maintain homeostasis
by pumping out
excess water.

10. Animal-like Protists: Protozoans
Phylum Ciliophora (ciliates) – Paramecium conjugation

11. Animal-like Protists: Protozoans
Phylum Sporozoa
•Nonmotile parasites
•Produce small infective cells called sporozoites
•Complex life cycle usually involving more than one host
•Cause a number of diseases, including malaria
• Ex: Plasmodium

12. Animal-like Protists: Protozoans
Phylum Sporozoa – Plasmodium Life Cycle

13. Other Protistan Diseases
African Sleeping sickness – Trypanosomiasis spread by
the bite of the tsetse fly.
Amebic Dysentery – severe
diarrhea caused by
contaminated drinking water
infested with Entamoeba or
Giardia.

14. Plant-like Protists: Unicellular Algae
Phylum Euglenophyta
•Primarily photosynthetic
•Most live in fresh water
•Possess 2 unequal flagella
•Lack cell walls
•Ex: Euglena

15. Plant-like Protists: Unicellular Algae
Phylum Chrysophyta (golden algae)
•Most photosynthetic
•Aquatic & mostly
unicellular
•Contain yellow-brown
pigments
•Ex: Thalassiosira &
Dinobryon

16. Plant-like Protists: Unicellular Algae
Phylum Bacillariophyta (diatoms)
•Live almost entirely in salt water.
•Unique cell walls rich in silicon
•Among the most abundant organisms on earth.

17. Plant-like Protists: Unicellular Algae
Phylum Pyrrophyta (Dinoflagellates)
•Two flagella
•Some are luminescent
•Many are symbiotic
•Most live in salt water & photosynthetic
•Rigid cell walls composed of cellulose
•Ex: Gonyaulux, Noctiluca &
Karenia (red tide)
Karenia

18. Plant-like Protists: Red Algae
Phylum Rhodophyta – red algae
•Live almost entirely in salt water
•Multicellular
•Contain red pigment phycobilins
•Ex: Chondrus (Irish moss) &
coralline algae

19. Plant-like Protists: Brown Algae
Phylum Phaeophyta – Brown algae
•Live almost entirely in salt water
•Multicellular
•Contain brown pigment fucoxanthin
•Ex: Kelp & Sargassum

20. Plant-like Protists: Green Algae
Phylum Chlorophyta – green algae
•Live in fresh & salt water
•Unicellular, colonial & multicellular
•Chlorophylls & accessory pigments
similar to plants
•Food stored as starch
•Ex: Ulva, Chlamydomonas
& Spirogyra

21. Plant-like Protists: Green Algae
Phylum Chlorophyta – Chlamydomonas Reproduction

22. Plant-like Protists: Green Algae
Phylum Chlorophyta – Ulva Reproduction

23. Human Uses of Algae •Food •Thickening agent •Plastics & waxes
•Transistors
•Deodorant
•Paints & lubricants
•Component of agar

24. Fungus-like Protists •Heterotrophic
•Absorb nutrients from dead or decaying organic matter
•Have centrioles
•NO chitin cell walls!
•Ex: cellular slime molds, acellular slime molds, water
molds

25. Fungus-like Protists: Cellular
Slime Molds
Phylum Acrasiomycota – cellular slime mold
Spores develop into independent free-living amoeba-like
cells that may come together to form a multicellular
structure.
This structure forms a fruiting body that produces
spores.

26. Fungus-like Protists: Cellular
Slime Molds
Phylum Acrasiomycota (cellular slime mold) - Life Cycle

27. Fungus-like Protists: Acellular
Slime Molds
Phylum Myxomycota (acellular slime molds)
Spore develop into haploid cells that can switch between
flagellated and amoeba-like forms;
These haploid cells fuse to form a zygote that grows into
a plasmodium, which ultimately forms spore-producing
fruiting bodies.

28. Fungus-like Protists: Acellular
Slime Molds
Phylum Myxomycota (acellular slime molds) – Life Cycle

29. Fungus-like Protists: Water Molds
Phylum Oomycota (water molds)
•Unicellular or multicellular
•Mostly aquatic
•Cell walls of cellulose
•Ex: Phytophthora infestans

30. Fungus-like Protists: Water Molds
Phylum Oomycota (water molds) – Life Cycle

31. Water Molds & Potato Famine
In 1845, Ireland, the potato crops
were devastated by Phytophthora
infestans. Between 1845 – 1851,
over 1 million Irish people died of
starvation or disease.
During that same time over 1 million
people emigrated from Ireland to
the United States and other
countries.