Protists are a diverse kingdom of eukaryotic organisms that are not classified as plants, animals, or fungi. They include both single-celled and multicellular organisms, many of which are aquatic. Protists can be categorized as animal-like, plant-like, or fungus-like depending on their characteristics and behaviors. Animal-like protists include those that use pseudopods, cilia, or flagella to move and feed, as well as non-motile sporozoans that are often parasitic. Plant-like protists include unicellular algae that perform photosynthesis and release oxygen into the environment, providing an important food source. Fungus-like protists absorb nutrients

1. Kingdom Protista

2. Protists, What are they?
 Protists are defined by what they are
NOT…
 Eukaryotes that are not plants, animals,
or fungi
 Scientists believe they were the “1st
eukaryotic organisms”
 Most are unicellular (algae exception)
 Many are “aquatic”
 Very diverse kingdom

3. Protists and the Evolutionary
Tree

4. Animal-like Protist
 Heterotrophic organisms
 Distinguished by how they move :
1) flagella: long “tail-like” structure
2) pseudopods: “false feet”
extensions of cytoplasm
3) cilia: tiny “hair-like” structures
beat in unison
4) some immobile

5. Sarcodines
 Animallike protists use
pseudopods for
feeding and moving
 Ex) Amoeba
Food

6. Ciliates
 Animallike protists use
cilia for feeding and
movement
 Ex) Paramecium

7. Zooflagellates
 Animallike protists swim
using flagella
 Trypanosoma protist
spread by the bite of tsetse
fly causes African Sleeping
Sickness
 Giardia can contaminate
water and cause digestive
problems
 Trichonympha lives in
mutualistic relationship
with termites

8. Sporozoans
 Animallike protists that do not move on their own and
are parasitic
 Plasmodium sporozoan causes malaria
 Sporozoan parasite is carried by female Anopheles
mosquito

9. Plasmodium Life Cycle
 Mosquito bites human
parasite injected
• Parasites invade liver
reproduce and develop
• Liver cells burst and
parasites move red
blood cells
• RBC burst person
experiences anemia,
fever, chills, may result in
death
• Parasites may then move
into other RBC or are
picked up by mosquito
and transferred to
another person

10. Plantlike Protists: Unicellular
Algae
 Photoautotrophs- contain chlorophyll
and carry out photosynthesis
 Often called “phytoplankton”- small
photosynthetic organisms near the surface
of ocean
 Phytoplankton carries out
photosynthesis releasing oxygen into
the atmosphere
 Phytoplankton important food source for
many “filter feeders”

11. Euglenophytes
 Plantlikeprotists that have flagella
chloroplast, but no cell wall.
 Ex) Euglena

12. Diatoms
 Produce thin, delicate cell walls made of
silicon
 Used in toothpaste, paints on license
plates, dynamite

13. Plantlike Protists: Algae
 Red Algae-
mostly multicellular
algae contains special
pigments that allows it
to live deep areas of
water
 Brown Algae-
all multicellular and
most are found in
marine environments
(ex: Kelp)

14. Plantlike Protists: Algae
 Green Algae- some are unicellular, some form
colonies, few are multicellular
Volvox
Chlamydomona
s
Sea Lettuce

15. Humans and Algae
• Humans understand many beneficial uses of
algae:
1) Used to make nutrient agar
2) Used as ingredient in ice cream, pudding,
salad dressing, syrups
3) Food source – humans and other animals
4) Releases oxygen from photosynthesis
• Algae causes harm in “algal blooms” –
depletes water of nutrients and oxygen

16. Funguslike Protists
 Heterotrophic protists that absorb nutrients, but
lack cell walls with chitin
 Ex) Slime molds- found near moist, rotting logs
and composts
 Ex) Water molds – can be parasitic and cause
“ick” in fish