Transcript Title of Presentation

Biology Chapter 19: Protists
Section 1: Introduction to Protists
Protists
Protists are usually classified by what they
are not: they are not animals, plants, or
fungi.
They belong to the Kingdom Protista which
was created to include this diverse group
of over 200,000 organisms
All protists are eukaryotes. Eukaryotic cells
contain membrane-bound organelles.
Protists
Like all eukaryotes, the DNA of protists is
found within the membrane-bound
nucleus.
Some protists reproduce asexually by
mitosis, while others exchange genetic
material during meiosis.
Classifying Protists
Because they are such a diverse group of
organisms, some scientists classify protists
by their method of obtaining nutrients.
Protists are divided into three groups using
this method:
Animal like protists, Plant like protists, and
Fungus like protists
Classifying Protists
The protozoan shown below is an example
of an animal-like protist because it is a
heterotroph.
Animal-like Protists
An amoeba is an example of a unicellular
animal-like protist or protozoan. Protozoans
are heterotrophs and usually ingest bacteria,
algae, or other protozoans.
The amoeba shown is ingesting another
unicellular protozoan – a paramecium.
Plant-like Protists
A giant kelp is an example of a plantlike
protist that makes its own food through
photosynthesis. Plantlike protists are
commonly referred to as algae.
Fungus-like Protists
The water mold is an example of a funguslike
protist that can absorb nutrients from a dead
salamander.
Funguslike protists are similar to fungi
because they absorb their nutrients from
other organisms.
Fungus and funguslike protists differ in the
composition of their cell wall, and funguslike
protists contain centrioles (small, cylindrical
organelles.
Fungus-like Protists
The Protists
Animal-like protists (Protozoan)
Ciliates, amoebas, apicomplexans, and zoo
flagellates
Plantlike protists (Algae)
Euglenoids, diatoms, dinoflagellates, green algae,
red algae, brown algae, yellow-green algae, and
golden-brown algae
Funguslike protists
Slime molds, water molds, and downy mildews
Animal-like protists (Protozoan)
Considered animal-like because they consume other
organisms for food
Some are parasites
Plantlike protists (Algae)
Considered plantlike because they make their own
food through photosynthesis
Some consume other organisms or are parasites when
light is unavailable for photosynthesis.
Funguslike protists
Considered funguslike because they feed on decaying
organic matter and absorb nutrients through their cell
walls.
Some slime molds consume other organisms and a
few slime molds are parasites
Habitats
Protists typically are found in damp or aquatic
environments such as decaying leaves, damp
soil, ponds, streams, and oceans.
Protists also live in symbiotic relationships (a
close ecological relationship)
Microsporidia are microscopic protozoans that
cause disease in insects.
Origin of Protists
The theory of endosymbiosis suggests that
eukaryotes, including protists, formed when a
large prokaryote engulfed a smaller
prokaryote.
The two organisms lived symbiotically and
eventually the organisms evolved into a
single, more highly developed organisms.
Origin of Protists