2008 kingdom protista ch 27 -...

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1 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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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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• Chaos chaos

• Nagleria fowleri– Causes Primary amoebic meningitis (PAM)

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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:

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• Common Spirogyraforms dense mats of filaments (chains of cell) and is able to reproduce sexually by conjugation.

Slime and Water Molds• Are fungal like in appearance• Slime molds engulf nutrients much like amoebas• Water molds form fungal like hyphae to decompose

organic mater in water