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Protists
Kingdom Protista is the most diverse of all the
kingdoms.
Are protists eukaryotes or prokaryotes?
Protists
Protists can be animal-like, plantlike, or funguslike.
• Protists are eukaryotes that are not animals, plants, or
fungi.
Protists
• Animal-like protists consume other organisms.
– heterotrophs
– single-celled
Protists
• Plantlike protists are photosynthetic.
– single-celled, colonial, or multicellular
– no roots, stems, or leaves
Protists
• Funguslike protists decompose dead organisms.
– heterotrophs
– can move, whereas fungi cannot
Protists
Protists are difficult to classify.
• Protista is one kingdom in the domain Eukarya.
Protists
• Protist classification will likely change.
Protists
II. Animal-like Protists
Animal-like protists are single-celled heterotrophs
that can move.
Protists
Animal-like protists move in various ways.
• Animal-like protists are often called protozoa.
macronucleus
contractile vacuole
food vacuole
oral groove
micronucleus
cilia
Protists
• Some protozoa move with flagella
Protists
• Some protists move with pseudopods.
– change shape as they move
– amoebas, for example
Protists
• Some protozoa move with cilia.
– cilia help protists swim and capture food
macronucleus
contractile vacuole
food vacuole
oral groove
micronucleus
cilia
Protists
Paramecia have contractile vacuoles to expel excess
water.
To avoid an obstacle, they back up, and move away in
an avoidance reaction.
Protists
Some animal-like protists cause disease.
human liver
sporozoites
• Malaria is caused by
Plasmodium and spread by
mosquitoes.
liver cells
developed
parasites
red blood
cells
Malaria Infection
Protists
Trypanosoma causes African sleeping sickness
Protists
Giardia is contracted from contaminated water
Protists
Protozoa can be beneficial
• One protozoan lives inside termites, digests
wood.
• Both species benefit, so this is called mutualism.
Protists
III. Plantlike Protists
Algae are plantlike protists.
Plantlike protists can be single-celled or multicellular.
colony
daughter colony
Protists
Daughter colonies leaving the mother colony.
Protists
A. Euglenoids are a large group of plantlike protists.
– mostly photosynthetic, have one or two flagella
pellicle
contractile
vacuole
nucleus
flagellum
chloroplast
eye spot
Protists
• Euglena moves toward the light, which is known as a
positive phototropism.
• Has a red eyespot, which is light sensitive
Protists
B. Dinoflagellates are marine plantlike protists.
–may be bioluminescent
– can cause red tide
Dinoflagellates
Protists
Noctiluca scintillans
Protists
C. Diatoms are plantlike protists with shells.
– shells made of silica
– produce large amounts of oxygen
Protists
More diatoms
Protists
• Multicellular algae are classified by their pigments.
– Green algae
– Brown algae
– Red algae
Protists
Red algae is used to make agar, food thickener, and
medicine capsules.
Protists
Spirogyra : a type of green algae
Protists
IV. Fungus-like protists
• include slime molds and water molds
• decomposers, like fungi
• can move, like animals
Protists
•
Slime molds
Protists
• Water molds are freshwater, funguslike protists.
– one type of water mold caused Great Potato Famine
of Ireland in the 1800’s
– made of branching
strands of cells
– can be parasites of
plants or fish
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