Kingdom Protista

The Link Between Bacteria and the Multicellular World There are plant-like protists that photosynthesize Dinoflagellates Euglena Diatoms Algae

The Link Between Bacteria and the Multicellular World Some are carnivorous protists that are hunters Amoebas Ciliates

The Link Between Bacteria and the Multicellular World Finally, some are like fungus, because they absorb nutrients from the surroundings and produce spores. Slime molds.

Protist: Characteristics All are Eukaryotic Some motile, some not Some single-celled, some multicellular. Variety of Ways to Get Energy Some are Carnivorous Photosynthetic Chemoautotrophic Detritivores

Characteristics Reproduction Primarily Asexual Budding Fragmentation Spores Sexual (less common but does happen) Many events happen in times of stress Male + Female gametes Sometimes, protists

Protista: General Characteristics

Classification and Phylogeny diplomonads Flagellated Protozoans parabasalids trypanosomes euglenoids radiolarians foraminiferans prokaryotic ancestor ciliates Alveolates dinoflagellates apicomplexans water molds diatoms Stramenopiles brown algae Figure 22.2 Single-celled protists include (a) amoebas, (b) euglenoids, and (c) diatoms. Most red algae (d) and all brown algae (e) are multicelled. (f) One proposed eukaryotic family tree with traditional protist groups indicated by tan boxes. Notice that the protists are not united as a single lineage. Figure It Out: Are land plants more closely related to the red algae or the brown algae? Answer: red algae red algae chlorophyte algae Green Algae charophyte algae land plants amoebas Amoebozoans slime molds fungi choanoflagellates animals

Group: Flagellated Protozoans Flagellated protozoans are single-celled protists covered by a pellicle (proteins that help cells retain shape) They swim in lakes, seas, and the body fluids of animals They are typically heterotrophic and reproduce asexually by binary fission

Trypanosomes and Other Kinetoplastids Kinetoplastids are flagellated protozoans with a single large mitochondrion Trypanosomes include human pathogens that are transmitted by insects African sleeping sickness (T. brucei) is spread by tsetse flies Chagas disease (T. cruzi) is spread by bloodsucking bugs

Human Disease Trypanosoma African sleeping sickness Transmitted by tsetse fly Causes fever, mental deterioration and coma

Phylum Zoomastigina No means of locomotion- most are parasitic and don’t need it Sexual reproduction present Environment- parasitic-aquatic

Human Disease Giardia Causes giardiasis Sever diarrhea and intestinal cramps Parasite in contaminated water Thousands of cases annually in U.S. Not usually fatal, but, you can imagine, uncomfortable.                                 A SEM micrograph of the small intestine of a gerbil infested with Giardia reveals a mucosa surface almost entirely obscured by attached trophozoites

The Euglenoids Euglenoids are flagellated protists related to kinetoplastids that do not infect humans Most prey on bacteria Some have chloroplasts that evolved from green algae and can detect light with an eyespot Most live in freshwater and have contractile vacuoles that expel excess water

Foraminiferans & Radiolarians Heterotrophic single cells with chalky or glassy shells live in great numbers in the world’s oceans; cytoplasm extends through many pores. Most forams live on the seafloor; others drift as part of the plankton.

Phylum Actinopoda Radiolarians Silica test Pseudopodia used for food getting Asexual reproduction Mostly marine

Phylum Foraminifera Forams Locomotion and food getting by pseudopodia Calcium carbonate test Environment- primarily marine

Group: Alveolates/ Ciliates Ciliates are heterotrophic single cells that move about with the help of cilia Ciliates reproduce asexually by binary fission or sexually by conjugation.

Phylum Ciliophora Locomotion and food getting by cilia Pellicle present maintains shape Contractile vacuoles remove excess water Sexual reproduction by conjugation Environment- aquatic Heterotrophic & parasitic

Paramecium Unicellular Heterotrophic Cilia Requires oxygen to live = aerobic environment Asexual & Sexual Reproduction Special Quality 2 nucleii Found in most aquatic environments

Phylum Ciliophora Stentor Largest freshwater protozoan Can regenerate body parts Cilia covers body for movement & feeding

This organism is aggressive and has a huge appetite Phylum Ciliophora Didinium This organism is aggressive and has a huge appetite

Didinium feeding Attaches to paramecium Starts to ingest Almost completely engulfed

Phylum Apicomplexa Protozoan that causes malaria Plasmodium enters bloodstream, travels to liver cells, where they divide and release new spores into the bloodstream. Parasitic No locomotion Reproduce asexually Transmitted by bite of infected mosquito Destroys red blood cells                                

Group: Stramenopiles “Red Algae” Brown algae are multi-celled protists that live in temperate or cool seas; ranging from microscopic filaments to giant kelp Some brown algae are used commercially Thickeners (algins), food, fertilizer, herbal supplements (bladderwrack)

Diatoms Diatoms are single-celled or colonial protists that have a two-part silica shell Shells accumulate on the seafloor (diatomaceous earth) Most are photosynthetic, with a brown accessory pigment (fucoxanthin) Major components of phytoplankton

Group: Red Algae Red algae are mostly multi-celled marine algae that live in clear, warm waters Red accessory pigments (phycobilins) allow red algae to live at greater depths than other algae Red and green algae share a common ancestor with chloroplasts derived from cyanobacteria Life cycles vary and are often complex, with both asexual and sexual phases; there is no flagellated stage.

Group: Green Algae Most green algae are chlorophytes Chlorella: Single celled, grown as health food Chlamydomonas: Single celled, freshwater alga Volvox: Colonial, freshwater alga Cladophora: Forms long filaments Ulva: “Sea lettuce” Codium fragilis: Branching marine alga Charophyte algae include several lineages that form a clade with land plants Desmids: A single-celled, freshwater group Spirogyra: Forms long filaments Stoneworts (Chara): Closely related to land plants

Group: Amoebozoans Amoebozoans send out pseudopods, move about, and capture food Most have no cell walls, shell, or pellicles Amoebas live as single cells Example: Amoeba proteus, a freshwater predator Slime molds are “social amoebas” Plasmodial and cellular slime molds Plasmodial slime molds spend most of their lives as a plasmodium A streaming multinucleated mass that feeds on microbes and organic matter Undergoes mitosis many times without cell division Develops into spore-bearing fruiting bodies

Phylum: Sarcodina Amoebas Unicellular Have pseudopodia = “false foot” which is an extension of the cytoplasm Pseudopodia for locomotion & feeding Reproduce asexually Most are free-living, some parasitic Found in soil, marine and freshwater Amoebas

Amoeba Structure

Amoeba locomotion & feeding Endocytosis (Phagocytosis) Digestion by enzymes Distinguish between food and non-food

Recap Protists represent the kingdom where evolutionary adaptations allowed for the development of plants, fungus, and animals from single-celled bacteria. Protists have numerous characteristics that allow for grouping. Some protists are good for us: provide nutrients, photosynthesize, etc. Some protists cause disease: malaria, African sleeping sickness, giardiasis.