Transcript Chapter 20: Protists

Chapter 20: Protists
Biology- Kirby
20-1: The Kingdom Protista
• Protist- any organism that is not a
plant, animal, fungus, or prokaryote.
• Protists are eukaryotes, and most are
unicellular.
• The first eukaryotic organisms on
Earth were protists (1.5 billion years
ago).
20-1: The Kingdom Protista
• 3 types of protists:
– Animallike- heterotrophs
– Plantlike- autotrophs
– Funguslike- external digestion such
as decomposers or parasites.
20-2: Animallike Protists:
Protozoans
• There are 4 types of protozoans
classified by their movement:
– Zooflagellates
– Sarcodines
– Ciliates
– Sporozoans
20-2: Animallike Protists:
Protozoans
• Zooflagellates- move through aquatic
environments with flagella.
• They can have more than 1 flagella.
• Able to absorb food through cell
membrane.
• Most reproduce asexually by mitosis
and cytokinesis.
• Some reproduce sexually by meiosis
and the formation of gametes.
20-2: Animallike Protists:
Protozoans
• Sarcodines- use pseudopods for
feeding and movement.
• Pseupod- “false foot”
• Example: Amoeba- capture and digest
food by forming a food vacuole with
its cytoplasm.
• They reproduce by mitosis and
cytokinesis.
20-2: Animallike Protists:
Protozoans
• Ciliates- use cilia for feeding and
movement.
• Cilia- short hairlike projections similar
to flagella. Cilia move together, or
beat, and move the organism very
quickly.
• Example: Paramecium- have a
macronucleus and a micronucleus.
• Cilia sweep food into the gullet.
20-2: Animallike Protists:
Protozoans
• Continued:
• Waste exit through an anal pore in
the membrane.
• A cavity called contractile vacuole holds
and expels water.
• Usually reproduce asexually by mitosis
and cytokinesis. Under stress,
paramecium undergo conjugation.
20-2: Animallike Protists:
Protozoans
• Sporozoans- do not move on their
own; parasitic.
• Attaches itself to a host and lives
inside it.
• Some animallike protists cause
diseases like malaria and African
sleeping sickness.
• Others are beneficial to organisms.
20-2: Animallike Protists:
Protozoans
• Zooflagellates
• Sarcodines
• Ciliates
• Sporozoans
20-3: Plantlike ProtistsUnicellular Algae
• Plantlike protists are called algae.
• They contain chlorophyll which makes
them appear green.
• Some scientists think algae are more
closely related to plants; but we
consider them to be protists.
20-3: Plantlike ProtistsUnicellular Algae
• Accessory pigments- absorb light at
different wavelengths than
chlorophyll- give algae a range of
color.
• There are 4 phyla of unicellular algae:
–
–
–
–
Euglenophytes
Chrysophytes
Diatoms
Dinoflagellates
20-3: Plantlike ProtistsUnicellular Algae
• Euglenophytes:
• Plantlike protists that have 2 flagella
and no cell wall.
• Have an eyespot which allows the
organism to find sunlight.
• Can also live as heterotrophs by
absorbing nutrients.
20-3: Plantlike ProtistsUnicellular Algae
• Chrysophytes:
• Means “golden plants” because they
have gold-colored chloroplasts.
• Diatoms:
• Produce thin cell walls made of silicon
which make the walls look like glass.
20-3: Plantlike ProtistsUnicellular Algae
• Dinoflagellates:
• Half are autotrophs, half are
heterotrophs.
• Many are luminescent and give off light
when agitated by sudden movement in
water.
20-4: Plantlike Protists-Red,
Brown, & Green Algae
• There are 3 phyla of multicellular algae:
– Red algae
– Brown algae
– Green algae
20-4: Plantlike Protists-Red,
Brown, & Green Algae
• Red algae:
• Able to live deep in the water.
• Have chlorophyll a and reddish
accessory pigments called phycobilins.
• Important to the formation of coral
reefs.
20-4: Plantlike Protists-Red,
Brown, & Green Algae
• Brown algae:
• Contain chlorophyll a and c, and a
brown accessory pigment called
fucoxanthin.
• Largest and most complex of the algae.
• Live in cool, shallow waters.
20-4: Plantlike Protists-Red,
Brown, & Green Algae
• Green algae:
• Contain chlorophyll a and b, and
cellulose in cell walls.
• Live in fresh and salt water.
• Unicellular green algae- 2 flagella &
single chloroplast.
• Colonial green algae- cells are stacked.
• Multicellular green algae- has
specialized cells & lives on rocky coasts.
20-4: Plantlike Protists-Red,
Brown, & Green Algae
• Green algae Reproduction:
• Life cycle includes both a diploid and
haploid generation.
20-5: Funguslike Protists
• Funguslike protists are heterotrophs
that absorb nutrients from
dead/decaying matter.
• Slime molds- funguslike protists that
recycle organic material.
– Cellular slime molds- individual cells
remain separated during life cycle.
– Acellular slime molds- cells fuse to
form large cells with many nuclei
called plasmodia.
20-5: Funguslike Protists
• Water molds- thrive on dead/decaying
matter in water & some are plant
parasites on land.
• Produce thin filaments called hyphae
which aid in reproduction.
• Slime and water molds are very
beneficial because they help
decompose matter, but some can
cause plant diseases.