Kingdom Protista Chapter 19

What is a protist? Protists may be: Are all eukaryotes. unicellular or multicellular. microscopic to very large. heterotrophic or autotrophic. beneficial, parasitic, or innocuous. Are all eukaryotes. There are 3 major categories of protists: animal-like protists plant-like protists fungus-like protists

Protozoa: The animal-like protists unicellular heterotrophic reproduction usually asexually sometimes sexually 4 main groups amoebas flagellates ciliates sporozoans

Phylum Rhizopoda: The Amoebas Are shapeless protists Move and feed with the aid of cytoplasm filled projections called pseudopodia (false foot) Live in mostly marine environments, but are also found in freshwater environments

Phylum Zoomastigina: The Flagellates Protozoans with one or more flagella Some are parasites ex. Trypanosoma brucei (African sleeping sickness) Some are beneficial ex. Trichonympha spp. (termites)

Phylum Ciliophora: The Ciliates Are covered with cilia that aid in locomotion Live in aquatic environments ex. Paramecium

Phylum Sporozoa: The Sporozoans Most produce spores spore is a reproductive cell forms without fertilization All are internal parasites Have complex life cycles Ex. Plasmodium, which causes malaria

Algae: The plant-like protists Are photosynthetic autotrophs Are unicellular or multi-cellular Unicellular (also know as phytoplankton) euglena diatoms dinoflagellates Multicellular: red algae brown algae green algae

Phylum Euglenophyta: The Euglenoids Are unicellular Are both autotrophic and heterotrophic Have a flagella Photosynthesize when light is favorable Ingest food when light is not favorable Do NOT have a cell wall, but have a flexible pellicle made of protein

Phylum Bacillariophyta: The Diatoms Are unicellular Photosynthetic autotrophs Have shells composed of silica (SiO2) Aquatic environments

Phylum Dinoflagellata: Dinoflagellates Have cell walls composed of cellulose Have two flagella located in grooves at right angles to each other Mostly marine Some live in symbiotic relationships ex. coral Some are toxic ex. Gonyaulux catanella (red tide)

The Multicellular Algae: 3 Phyla Rhodaphyta: red algae Live in deep waters Phaeophyta: brown algae Include kelp Have air bladders to float Chlorophyta: green algae Most diverse (>7000 spp.) Ex. Volvox & Spirogyra

The Fungus-like Protists Are all heterotrophic decomposers Two main groups with 3 phyla The slime molds Myxomycota Acrasiomycota Water molds and downy mildews Oomycota

Phylum Myxomycota Consist of the plasmodial slime molds Plasmodium: mass of cytoplasm that contains many diploid nuclei but contain no cell walls or membranes Move at ~2.5cm/hr Can reach 1m+ in diameter and contain thousands of nuclei Can reproduce asexually or sexually

Phylum Acrasiomycota Consist of the cellular slime molds Spend part of their life as a single amoeboid cell Forms a mass, like a plasmodium, when food is scarce but is multicellular with plasma membranes Cells are haploid for their entire life cycle.

Phylum Oomycota Water molds Downy mildews Appear white and fuzzy Produce flagellated reproductive cells Downy mildews Have caused major crop destruction Phytophthora infestans : responsible for the Irish potato famine of the 1840’s