2008 kingdom protista ch 27 -...
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Kingdom Protista
Protista• Traditionally a kingdom level taxon• Current evidence places organisms in as
many as 3-5 kingdoms• We will classify all:
– Unicellular or simple colonial– Eukaryotic– Organisms that are not fungi, plants or animals
as members of the kingdom protista
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Members of the Kingdom protista
• Are traditionally studied by breaking the kingdom into three informal groups:– Algae – capable of photosynthesis– Slime and water molds – heterotrophic
saprophytes– Protozoans – heterotrophic animal like;
parasites
Giardia
• – Giardia lamblia– Causes giardiasis; aka
beaver fever; drinking contaminated water • Characteristics:
– Lack mitochondria– Multiple flagella– Two nuclei
Protozoans:
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Trichomonas
– Trichomonas vaginalis• Considered an STD
• Characteristics:– Multiple flagella– Undulating membrane– No mitochondria
Protozoans:
Flagellates
• Characteristics:– Single large mitochondria– Large flagellum– Undulating membrane– All are symbiotic; many
are important parasites– (symbiosis – parasitic,
mutualistic, commensal)
Protozoans:
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• Examples : Trypanosoma brucei and T. gambiense cause African Sleeping sickness
Life cycle includes a vector, an organism that transmits the infective stage of a parasite to a suitable host.
The vector for African Sleeping sickness is Glossina, the Tse Tsefly
• T. cruzi causes Chaga’s disease. Present in much of South, Central and parts of North America.
• Vector is an insect – blood sucking cone-nosed bug
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Malaria• All are parasites• Infective stage – sporozoites
– These sporozoites have at their end (apex) a complex of organelles for penetrating host cells and tissues.
– Complex life cycle with sexual and asexual stages
– Example – Plasmodium causes malaria
Protozoans:
• Vector is a mosquito
• Currently affects over 300 million worldwide
• Know the life cycle!!!
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Ciliates
• Solitary aquatic protozoans• Cilia for locomotion• Generally reproduce asexually by binary fission
(cell division)• Do have a sexual form of reproduction as well;
simply for genetic diversity – conjugation• Pair of nuclei –macronucleus and micronucleus• Example : Paramecium
Protozoans:
During conjugation, micronuclei undergo meiosis and are swapped
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Amoebas• Uses pseudopodium (false foot) for:
– locomotion – Feeding – endocytosis called phagocytosis
Protozoans:
Examples
• Amoeba proteus
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• Entamoebahistolytica– Causes amoebic
dysentery
Euglena• Euglena – autotrophic when sunlight is available• Common in freshwater (aquatic) habitats
Algae:
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Diatoms• Unicellular algae with a delicate glass-like test made of silica – very
strong• Marine and freshwater forms (100,000 different species !)
Algae:
• Uses of diatoms– Producers in ecosystems– Diatomaceous earth deposits for filters,
pest control, nanotechnology
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Brown algae• Multicellular marine
algae• Resemble plants –
superficially; only as similar structures found in plants are analogous not homologous.
• Structure – Body = thallus– Consisting of
stipe, blades, and holdfast
Algae:
Importance of brown algae
• Kelp forests in marine ecosystems• Human consumption
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Red algae• Marine algae, smaller in general than phaeophytes• Multicellular, red accessory pigments for photosynthesis• Approx 6,000 spp.• Red algae are also important producers in marine ecosystems
and serve as food sources for humans as well (carrageenan)
Algae:
Green algae
• Named for green chloroplasts• Closely related to plants (probably the ancestor of land
plants was a green algae)• Very diverse phylum – some unicellular forms while
others are multicellular or colonial
Algae: