Protists Chapter  m Chapter 28 Protists

Introduction Eukaryotic Mostly unicellular (many colonial and multicellular forms) Exhibit more structural and functional diversity than any other eukaryotic group Most nutritionally diverse of all eukaryotes Photoautotrophs, heterotrophs, mixotrophs (combine photosynthesis and heterotrophic nutrition)

3 categories of nutritional diversity: 1.Ingestive – (animal-like) protozoa e.g., Amoeba, Paramecium 2.Absorptive – (fungal-like) plasmodial and cellular slime molds e.g., Phytophthora infestans 3.Photosynthetic – (plant-like) algae e.g., Spartina, red algae, Volvox

Introduction cont. Moist habitats e.g., oceans, lakes, damp soil, leaf litter, body fluids, tissues, cells of hosts, etc. Important components of plankton Phytoplankton produce over half of world’s organic carbon and oxygen Motile - flagella or cilia (but some move by cytoplasmic streaming, gliding or just floating) Reproduction – highly diverse (asexually and sexually)

Fig Green algae Amoebozoans Opisthokonts Alveolates Stramenopiles Diplomonads Parabasalids Euglenozoans Dinoflagellates Apicomplexans Ciliates Diatoms Golden algae Brown algae Oomycetes Excavata Chromalveolata Rhizaria Chlorarachniophytes Forams Radiolarians Archaeplastida Red algae Chlorophytes Charophyceans Land plants Unikonta Slime molds Gymnamoebas Entamoebas Nucleariids Fungi Choanoflagellates Animals

Diplomonads –anaerobic environments –two nuclei and multiple flagella –Many are parasitic (Giardia intestinalis) Fig. 28.3

trichomonads Figure 28.4 Trichomonas vaginalis, a parabasalid Flagella Undulating membrane 5 µm

Euglenozoa autotrophic but some are heterotrophic (predatory and pathogenic parasites) flagellates euglenids –characterized by an anterior pocket (or chamber) from which 1 or 2 flagella emerge (Euglena) and kinetoplastids –Single-large mitochondrion associated with the organelle, kinetoplast (that houses extranuclear DNA) (Trypanosoma)

Video: Euglena Motion Video: Euglena Motion

Trypanosoma causes sleeping sickness in humans (spread by the tsetse fly) Figure  m

Alveolates small membrane-bounded cavities (alveoli) under cell surfaces –Alveoli function is unknown

dinoflagellates phytoplankton (provide foundation in aquatic food chains) form blooms causing red tides (toxic) 1° output (from photosynthesis) is C, which is a major food source for the reef community Red tide

Apicomplexans Nearly all parasites of animals Some cause serious human diseases Most have intricate life cycles with both sexual and asexual stages (usually requiring 2 or more different host species for a complete life cycle) E.g., Plasmodium

Fig µm Inside human Liver Liver cell Merozoite (n) Red blood cells Gametocytes (n) Haploid (n) Diploid (2n) Key Merozoite Apex Red blood cell Zygote (2n) FERTILIZATION Gametes Inside mosquito MEIOSIS Oocyst Sporozoites (n)

Ciliates cilia (move and feed) asexual (binary fission), but uses conjugation for genetic diversity E.g., Paramecium and Stentor

Diatoms Glass-like walls made of silica Gliding movement Common in FW and M environments Diatomaceous earth (massive amounts of fossilized cell walls found in sediments) forensic applications

Golden Algae Cells typically biflagellated FW and M Most unicellular, some colonial Flagellum Colonial golden algae found in FW

Brown Algae Most marine, all multicellular Largest and most complex algae Found along temperate coasts E.g., seaweeds, kelp forests

Oomycetes (Water Molds) Heterotrophic, lack chloroplasts Biflagellated zoospores that infect others Cell wall made of cellulose E.g., Ick (cottony, fuzz on dead fish)

Foraminifera attached to rocks or sand in marine water Shells made of calcium carbonate, thereby explaining their abundance in the fossil record E.g., forams Figure µm

Red Algae usually multicellular Most marine, deep sea species Most abundant algae in coastal waters of the tropics E.g., Nori

Fig Bonnemaisonia hamifera 20 cm 8 mm Dulse (Palmaria palmata) Nori. The red alga Porphyra is the source of a traditional Japanese food. The seaweed is grown on nets in shallow coastal waters. The harvested seaweed is spread on bamboo screens to dry. Paper-thin, glossy sheets of nori make a mineral-rich wrap for rice, seafood, and vegetables in sushi.

Green Algae Highly photosynthetic Most live in FW, some marine, some in damp soil, as symbionts in lichens, or in snow Closely related to land plants Chlorophyll a & b Unicellular, colonial, and multicellular forms

Fig

Fig j 20 µm 50 µm

Fig (a) Ulva, or sea lettuce (b) Caulerpa, an intertidal chloro- phyte 2 cm

Gymnamoebas Are common in soil, fw and M environments Most are heterotrophic (phagocytosis) –And actively seek and consume bacteria and other protists Video: Amoeba Pseudopodia Video: Amoeba Pseudopodia

Figure Pseudopodia 40 µm

Entamoebas parasites of vertebrates and some invertebrates Entamoeba histolytica –Causes amoebic dysentery in humans

Plasmodial Slime Molds Many species are brightly pigmented, usually yellow or orange At one point in the life cycle they form a mass called a plasmodium Figure cm

Cellular Slime Molds Cellular slime molds form multicellular aggregates –In which the cells remain separated by their membranes Dictyostelium discoideum