PROTISTS

The Hodge Podge Kingdom

Protists are Divided into 3 Catagories

• The animal-like protists

• The plant-like protists

• The fungi-like protists

Protists are

• Eukaryotic

• Can be unicellular or multicellular

• Can be motile or not (flagella and cilia)

• Can be photoautotrophs or chemoheterotrophs or both

• Contain 2 or more chromosomes with many histones and other proteins.

Animal-like Protists

• Phylum Sarcodina (Locomotion is via psuedopodia)

– Amoebas: Naked, soft-bodied cells that live in freshwater, marine and soil.

– Foraminiferans (many chambered test; composed of CaCO3): primarily marine

– Heliozoans: Have fine needle-like psuedopodia radiating from body like sun rays. Largely fresh water

– Radiolarians (test is composed of silicon dioxide) found in open, shallow waters.

Amoebida

Foraminiferans

Heliozoida

Radiolarian

More Radiolarians

Sarcodina

• Use ameoboid movement made possible by cytoplasmic streaming to get around.– Endoplasm (inner) pushes on ectoplasm

(outer) to create the arm-like extention.

• Because they live in an aquatic environment they need a contractile vacuole to regulate water pressure inside the cell.

Diseases associated with Sarcodina

• Ameobic dysentery: Entameoba histolytica

• Reproduction- Binary fission- Budding- formation of cysts during times of

stress.

Animal-like protists (cont.)

• Phylum Ciliophora– Paramecium- Reproduces via conjugation and

binary fission. - Important parts include oral groove,

pellicle, mouth pore, gullet, anal pore, macronucleus and micronucleus.

Animal-like protists: Ciliaphora cont.

• Reproduction:– Conjugation followed by binary

fission– Binary fission alone

• Parameciums divide along a transverse line

Paramecium

Cilliate (Bursaria)

• http://micro.magnet.fsu.edu/moviegallery/pondscum/protozoa/bursaria/index.html

Animal-like Protists (cont.)

• Phylum Mastigophora• Movement via flagella

– Trypanosoma brucei (African trypanosomiasis or sleeping sickness)

• Vector: tsetse fly

– Trypanosoma cruzi (Chaga’s disease)• Vector: Kissing bug

– Trichonomas vaginalis– Giardia lamblia (giardiasis)

Trypanosoma

Tsetse Fly

Giardia

Animal-like Protists (cont.)

• Phylum Sporozoa–Malaria: life cycle

–Toxoplasmosis

Anopheles mosquito

Toxoplama gondii (intracellular)

Plant-like Protists

• Characteristics–Autotrophs–Lack tissue differentiation–Unicellular and muticellular–Aquatic–Contain pyrenoids (organelles

that synthesize and store starch.

Plant-like Protists cont.

• Structure of thallus: body portion of the algae.–Body structure is divided into 3

types.• Unicellular E.g. phytoplankton• Colonial E.g. volvox• Filamentous e.g. Spirogyra• Multicellular e.g. Ulva

Plant-like Protists cont.• Classification

– They are classified based on color, type of chlorophyll, form of food-storage and cell wall composition.

• Reproduction– Some reproduce only via asexual

reproduction while other have both asexual and sexual reproduction. See later slides for details.

Plant-like Protists cont.

• Phylum: Euglenophyta– Euglena (euglenoid)– Photosynthetic pigments

• Chlorophylls a and b, carontenoids, xanthophyll.

– Movement by flagella. Stigma detects light and euglena move towards it.

– Can be heterotrophic if deprived of light.

Plant-like Protists cont.

• Phylum: Chrysophyta (the golden algae) Yellow-green algae

• Most are fresh water algae but a few are found in a marine environment.

• golden color due to the pigment fucoxanthin (a carotenoid) which masks the chlorophyll

• Stores much of its surplus energy as oil and are important in the formation of petroleum deposits

Plant-like Protists cont.

• Bacillariophyta: the diatoms– Abundant in both freshwater and

marine.– Have shells that are pill box-like that

consist of silicon dioxide. Each half of the shell is called a valve.• Some shells are centric (circular or

triangular) and are marine.• Others are pennate (rectangular) and

are found in freshwater. Move by threads that attach to water surface.

Plant-like Protists (cont.)

• Phylum Dinoflagellata– dinoflagellates– red tides (Gonyaulax catanella)

produces neurotoxin– Some have bioluminescence

(Noctiluca)– All have 2 flagella, are unicellular,

mostly marine and contain pigments chlorophyll, carotenoids, and other red pigments.

Noctiluca scintillans

Plant-like Protists (cont.)

• Phylum: Rhodophyta (the red algae) but may appear green, purple, or greenish-blk.

• Multicellular

• Tropical waters and along rocky coasts in colder waters.

• Pigments: chlorohyll, phycobilins (red/blue) Good at absorbing green and blue/green light waves which can penetrate below 100 m in water.

Rhodophyta cont.

• Some have cell walls coated with a sticky substance called carageenan (used in cosmetics, gelatin capsules and cheese).

• The cell walls contain agar which is extracted and used to make media for culturing microorganisms.

Plant-like Protists (cont.)

• Phylum: Phaeophyta (the brown algae)– All are multicellular

– Largest are kelp

– Pigments include chlorophyll and fucoxanthin

– Food is stored as laminarin

– Macrocysitis cell walls contain alginate (used as a stabilizer in ice cream).

Plant-like Protists (cont.)

• Phylum: Phaeophyta (cont.)– Parts of kelp

• Body is called thallus• “Roots” are called holdfasts• “Stems” are called stipe.• “Leaves” are called blades.

Air bladders keep thallus afloat allowing access to light

Sargassum serve as floating ecosystem

Contains a commercially important substance called alginate. Alginate is used as a stabilizer in most ice creams.

•The Sargasso Sea

Plant-like Protists(cont.)

• Phylum: Chlorophyta (the green algae)– It is believed that this group gave

rise to land plants.– Most diverse (7000 identified species)– Can be unicellular or multicellular, colonial or

sheets.– Found in fresh water and marine environments– Pigment mostly chorophyll– Store food as starch.– Many reproductive methods

• See Ulva for life cycle– Often have symbiotic relationships with fungi

(lichens).

Fungi-like Protists

• Chytrids (Phylum Chtidiomycota)

• Water molds (Phylum Oomycota)

• Slime molds– Acrasiomycota: Cellular slime molds

– Myxomycota: Plasmodial slime molds (acellular)

Chytrids (Phylum Chtidiomycota)

• Are believed to be the evolutionary link between protists and fungi (Share enzymes and biochemical pathways).

• Live in fresh water and marine• Some are saprobic decomposers while

others are parasites.• Single-celled species produce flagellated

asexual spores (1 reason it is in Protista).• Chitin reinforces cell wall.

– Cell walls are sieve like between cells allowing flow of cytoplasm throughout mycelium.

Water molds (Phylum Oomycota)

• Distantly related to red algae• Reproduction

– Produce flagellated asexual zoospores which germinate into long thread-like cells forming a thallus.

– Sexual reproduction occurs when a connecting tube is formed between oogonia and antheridia. Zygote (2n) develops into new thallus.

• Key decomposers of aquatic habitats• Some parasitize• Phytophtlora infestans caused “late blight”

and the great Irish potato famine.– Blight is a disease of plants characterized by

decay and discoloring of leaves.

Fungi-like protists cont.

• Slime molds contain 2 phylum– Acrasiomycota: Cellular slime

molds• Live as haploid cells that move like

amoebas. • Asexually reproduce. Sexual

reproduction rare or absent.– When food/water is scarce a chemical

is released causing them to gather into a pseudoplasmodium.

– Pseudoplasmodium produces fruiting body which produces haploid spores.

Acrasiomycota fruit bodies

Fungi-like protists cont

– Mxyomycota: plasmodial (acellular) slime mold• Acellular because the plamodium (group of

feeding cells) lack cell walls & appear as a mass of cytoplasm with thousands of nuclei.

• Each nuclei is diploid.• Mass phagocytizes decaying leaves/debris.• When food/water is scarce the plasmodium

crawls to an exposed area and forms a stalked fruiting body which undergoes meiosis to produce haploid spores. These spores will give rise to haploid reproductive cells which fuse to form a diploid nucleus.

• Mitosis occurs but cytokinesis never does.

Fuligo septica: The dog vomit slime mold