Transcript Protists - Needham.K12.ma.us

The Protist Kingdom
…And the 3 “Classic” Protists!
What is a Protist?
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Protists: Eukaryotic organisms that
cannot be classified as animals, plants, or
fungi.
Protists are very varied, but they do have
some similarities. Beside the fact that they
are all eukaryotic, they all live in moist
surroundings as well.
How Diverse?
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The protists kingdom is one of the most diverse.
Most are unicellular, although some are
multicellular.
Some are heterotrophs, some are autotrophs
and some are…. BOTH!
Some protists cannot move while some others
have no problem zipping around their
surroundings.
How are they grouped?
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Because protists are so varied, Scientist
group them into smaller categories:
Animal-like protists (protozoa)
 Plantlike protists (algae)
 Funguslike protists (funguslike)
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Though we will be discussing all protists in
class, this powerpoint will focus on the
animal-like protists.
Animal-like Protists
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Like animals, animal-like protists are
heterotrophs.
Most are able to move from place to place
to obtain food.
Unlike animals, animal-like protists are
unicellular.
Animal-like protists are also called
Protozoans.
Protozoans
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Just as protists are split into smaller
groups, so are protozoans. They can be
split into 4 categories based on the way
they move and get food.
The groups are:
 Protozoans
with pseudopods (sarcodines)
 Protozoans with cilia (ciliates)
 Protozoans with flagella (flagellates)
 Protozoans that are parasites
Protozoans with Pseudopods
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Protozoans that have pseudopods are
called sarcodines.
Pseudopod: Means “false foot”, it is a
temporary bulge of the cell that allows for
feeding and movement.
Pseudopods form when cytoplasm flows
toward one location and the rest of the cell
follows.
Amoeba
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Amoeba: Sarcodines that live in either
water or soil. They feed on bacteria and
smaller protists.
Like all sarcodines, amoebas move and
obtain food with their pseudopods.
Amoeba
Protozoans in fresh water
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Protozoans that live in fresh water have a big
problem. Water can move easily through the
cell membrane and too much can cause the cell
to burst (passive transport or osmosis).
Fortunately for these protozoans, they have a
contractile vacuole.
A contractile vacuole is a structure that collects
and expels excess water from the cell.
Protozoans with Cilia
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Protozoans with cilia are called ciliates.
Cilia: Hair like projections from a cell that move
with a wavelike motion.
Just like pseudopods, ciliates use cilia to move
and obtain food.
Ciliates have complex cells. Many have more
than one contractile vacuole and some (like
paramecium), have 2 nuclei.
The macronucleus (large) controls everyday
tasks and the micronucleus (small) aids in
reproduction.
Paramecium
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Paramecium: Ciliates that live mostly in
fresh water. Like amoebas, paramecia
feed on bacteria and smaller protists.
Like all ciliates, paramecia move and
obtain food with their cilia.
Paramecium
Protozoans with flagella
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Protists with flagella are called flagellates.
Flagella: Whip-like structure that allows
for movement.
Many flagellates form symbiotic
relationships, both good and bad.
Euglena
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Euglena: A common protozoa that lives in
fresh water.
In sunlight, euglena can make their own
food. What makes them bizarre is that
when the lights go down, they become
heterotrophic predators!
Like all flagellates, euglena move with a
flagellum.
Euglena
Parasitic Protozoans
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Protozoans that are parasitic feed on cells
and bodily fluids of their hosts.
They move in a variety of ways, some
have flagella and some depend on their
host for movement.
Some have more than one host, relying on
one organism for transport and one for
food.