Protists are a diverse group of eukaryotic organisms that include protozoa, algae, and fungus-like protists. They can be unicellular or multicellular, microscopic or large, and obtain energy through photosynthesis or consuming other organisms or organic matter. Major groups of protists include protozoa such as amoebas, flagellates, ciliates, and sporozoans; algae which perform photosynthesis; and fungus-like protists such as slime molds, water molds, and downy mildews. Protists play important roles in ecosystems as producers, decomposers, and causes of diseases.

1. Protists
What is a Protist?
Kingdom Protista contains the most diverse
organisms of all the kingdoms.
Protists may be unicellular or multicellular,
microscopic or very large, and heterotrophic or
autotrophic.
There is no such organism as a typical protist. The
characteristic that all protists share is that, unlike
bacteria, they are all eukaryotes.

2. Types of protists
1. Protozoa- animal like protists, (resemble animals
in the way they get food) all are unicellular
2. Algae- plantlike protists (photosynthesis to make
their food)
3. Fungus like protist (decompose dead organisms)
unlike fungi, funguslike protists are able to move
at some point in their life and do not have chitin
in their cell walls. Ex. Slime molds, water molds,
and downy mildews

3. Protists
Some protists cause diseases, such as malaria
and sleeping sickness, that result in millions of
human deaths throughout the world every year.
Unicellular algae produce much of the oxygen in
Earth’s atmosphere and are the basis of aquatic
food chains.

4. What is a protozoan?
All protozoans are unicellular heterotrophs that
feed on other organisms or dead organic matter.
They usually reproduce asexually, but some also
reproduce sexually.
4 main groups of protozoans
1. The amoebas
2. Flagellates
3. Ciliates
4. sporozoans

5. The amoebas: shapeless protists
Amoebas have no cell wall and form pseudopodia
to move food. As pseudopodia forms, the shape of
the cell changes and the amoeba moves.
Most live in salt water, there are freshwater ones
that live in the ooze of ponds.
Most amoebas commonly reproduce by asexual
reproduction.
When environmental conditions become
unfavorable, some types of amoebas form cysts
that can survive extreme conditions.

6. Naegleria fowleri- brain eating
ameoba

7. Flagellates: protozoans with flagella
Flagellates, which have one or more flagella to help
it move.
Some are parasites that cause disease in animals,
such as African sleeping sickness in humans.
Some have a mutualistic relationship with termites.
They live in the gut of termites they convert
cellulose from wood into a carbohydrates that both
they and their termite hosts can use.

8. Flagellates

9. Cilliates: protozoans with cilia
Ciliates, use the cilia that cover their bodies to
move.
Live in every kind of aquatic habitat- from ponds
and streams to oceans and sulfur springs.
Usually reproduces asexually by dividing and
separating into two daughter cells.

10. Ciliate

11. Sporozoans: parasitic protozoans
Sporozoans- most produce spores. A spore is a
reproductive cell that forms without fertilization
and produces a new organism.
All sporozoans are parasites. They live as
internal parasites in one or more hosts and have
complex life cycles.
Plasmodium are organisms that cause the
disease malaria in humans and other mammals
and in birds.

13. Algae
Photosynthesizing protists are called algae.
All algae contain up to four kinds of chlorophyll
as well as other photosynthetic pigments. These
pigments produce a variety of colors in algae,
including purple, rusty-red, olive-brown, yellow,
and golden-brown, and are a way of classifying
algae.

14. Algae
Algae include both unicellular and multicellular.
Unicellular algae
The photosynthesizing unicellular protists,
known as phytoplankton are one of the major
producers of nutrients and oxygen in aquatic
ecosystems.
Multicellular algae
May look like plants but they do not have roots,
stems or leaves.

15. Algae

16. Fungus like protists
The slime molds, the water molds, and the downy
mildews, consist of organisms with some funguslike
features like decompose organic materials.
Slime molds
Beautifully colored, ranging from brilliant yellow or
orange to rich blue violet, and jet black. The live in
cool, moist, shade places where they grow on
damp, organic matter, such as rotting leaves or
decaying tree stumps and logs.

17. Funguslike protists.

18. Water molds and downy mildews
Live in water or moist places.
Feed on dead organisms and others are plant
parasites.
Most water mold appear fuzzy, white growths
on decaying matter.
Downy mildews cause diseases in many plants.

19. Water molds and downy mildews