PROTISTS

Protists Protists: Unicellular eukaryotic organisms. Over 115,000 species Eukaryotic cells - contain membrane-bound organelles (particularly mitichondria & chloroplasts) Protists & eukaryotes probably evolved from a large eukaryotic cell ingesting a photosynthetic and oxygen metabolizing bacteria Known as endosymbiotic theory Two major classes of protists Animal-like protists Plant-like protists

Animal-like Protists Phylum Ciliophora (Cilia bearing protists) Aka "ciliates" Have cilia (short hairlike structures) on their plasma membranes Cilia rapidly beat and provide propulsion for the protist. Over 7000 species in this phylum. Example is paramecium.

Paramecium Large organisms ~305 micrometers long Important features: Have 2 nuclei Macronucleus (large) Micronucleus (smaller) Feed by forcing H2O into Gullet forming food vacuoles Excrete wastes through anal pore Excrete excess water through use of contractile vacuoles Move by coordinated movement of hair-like cilia.

More Paramecium

Phylum Sporozoa Usually parasitic in nature Example is Plasmodia which causes malaria. One of the most deadly diseases to man Malaria is transmitted by the Anopheles mosquito.

Lifecycle of Plasmodia

Phylum Sarcodina Protists with false feet Use extensions of cytoplasm to move and feed. Extensions are called pseudopods (false feet) Movement is by extending pseudopod, then the remainder of cytoplasm flows into extension. Feeding is done by extending 2 pseudopods around object and engulfing object, forming a food vacuole Examples are amoebas (amebas)

Amoebas

More amoebas

Plant-like Protists 5 phyla of plant-like protists Are usually photosynthetic, and also heterotrophic. All are unicellular, most are motile Example: Phylum Euglenophyta

Phylum Euglenophyta Example is euglena. Has a flagellum, is motile Is both heterotrophic & autotrophic Contains chloroplasts & is photosynthetic. Can become heterotrophic in low-light conditions

Euglena

Dinoflagellates Have 2 flagella for motility Often have a cellulose covering

Diatoms Most abundant form of marine algae. Form elaborate silicon (glass) shells to protect themselves Shell is porous to allow materials in/out of the cell.

Multicellular / Other Algae Are not generally true multicellular organisms, but rather "colonies" Show beginnings of specialized functions / tissues 3 types Green algae Red Algae Brown algae

Green algae (Chlorophyta) Contain chlorophyl a & b Most frequently found in fresh water Often colonial Volvox: a green colonial algae

Red Algae (Rhodophyta) Found in salt/brackish water Have additional pigments which give them a reddish color. In uncontrolled blooms, these organisms can cause serious ecological damage Red algeal bloom

Brown Algae (Rhodophyta) Most Plant-like of all algae. Include kelps Can grow to huge sizes (100') Most primitive plant like organism to show alternation of generations. Giant Kelp Forest

Fungus like Protists: Fungus like Protists: Act as decomposers Often have a slimy appearance/texture, hence their name. 3 types: Plasmodial slime molds Cellular slime molds Water molds

Plasmodial Slime Molds Can grow very large, however, is still a single cell (with many nuclei) Feeding stage is called a plasmodium. Forms fruiting bodies under stress.

Cellular Slime Molds: Cellular Slime Molds: Exists a majority of its life cycle as an amoeba In  times of stress these amoebas unite to form a Pseudoplasmodium, which crawls to another location (slug form), and forms a fruiting body

Water molds: Water molds: Completely aquatic Often decomposers Sometimes parasitic Water mold attacking a fish