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Protists
Chapter 21
What are Protists?
• Protists are eukaryotic organisms that
can’t be classified as fungi, plants, or
animals
• Multicellularity found
in some prokaryotes
allow cells to specialize,
which, in turn, allows
for the development
of tissues, organs,
and organ systems
Reproduction
• Protists can reproduce asexually by
– Binary fission: Reproduction by replicating
DNA and splitting in half
– Budding: When part of a parent organism
pinches off and forms a new organism
– Fragmentation: When part of an organism is
broken off and a new organism starts
• Protists can reproduce sexually as a
response to environmental stress
Groups of Protists
• Protists are commonly grouped by how
they get nutrition
• This leaves us with three groups:
Animal-Like Protists
• These protists ingest other organisms to
obtain energy (heterotrophic by ingestion),
like animals!
• They are all unicellular
• Most can move
Plant-Like Protists
• These protists get energy through
photosynthesis, like plants!
• Most are multicellular
Fungus-Like Protists
• These protists absorb nutrients from the
environment (heterotrophic by absorption),
like fungi!
Pathogenic Protists
• Malaria is caused by the animal-like
protists Plasmodium
• It is spread by the bite of a mosquito
• If left untreated, it can cause rupture of the
spleen, kidney failure, coma, brain
damage, and death
• Malaria Video