what are protozoa? proto = first zoa = animals single-celled eukaryotic organisms
TRANSCRIPT
What are Protozoa?
proto = first
zoa = animals
single-celled eukaryotic organisms
Combined Protein Consensus Tree
From S.L. Baldauf (1999) Am. Nat. 154:S178
What are Protozoa?
proto = first
zoa = plant/animal?
Unicellular eukaryotes• protozoa• algae• yeast/fungi• slime molds
Protozoan SizesPlasmodiummerozoites
2-5 m
Paramecium 200-500 mSpirostomumambiguum
3 mm
Nummulites(fossilized)
7-13 cm
m = micron = 10-6 meters (1/1000 mm)
Protozoan Life Styles• absorb solutes (osmotrophy)• ingest particulates (phagotrophy)
- predation on bacteria or other protozoa
- pinocytosis (fluid uptake)• photosynthetic (autotrophy)• combinations (heterotrophy)
free-living vs. symbiosis
symbiosisclose association of twodifferent organisms
mutualism beneficial to both organisms
commensalismbeneficial for one of theorganisms, but the other isneither benefited nor harmed
parasitismone organism (the parasite)living at the expense of theother (the host)
pathogen parasites that injure their host
Protozoan Reproduction
Asexualbinary fissionmultiple fissionbudding
Sexualfusion of gametesconjugation
• >200,000 named species
• ~10,000 parasites• ~20 human
pathogens
ProtozoanDiversity
Mechanism Subgroupameboid movement amebas
flagella flagellates
cilia ciliates
gliding motility sporozoa
Protozoan Motility
Protozoan Taxonomy• confused, controversial and constantly
changing• originally based on motility (light microscope)• ultrastructural (electron microscope) criteria
used since 1960’s• molecular data can help with evolutionary
relationships• monophyletic groups
• descended from common ancestor• kinetoplastids, apicomplexa, ciliates
• polyphyletic groups• multiple ancestors• amebas and flagellates
Genus + species
What are Protozoa?• unicellular eukaryote• ?• ?• ?• extremely diverse
But not simple!