Drop of Water  Protista is a paraphyletic clade in which protists can more closely be related to plants, fungi, and animals than other protists  Eukaryotic nature with more structural and functional diversity than any group of organisms  Some are unicellular, others are colonial and multicellular

Diverse Assortment  Three possible nutritional modes: a. photoautotrophs b. heterotrophs c. combination of both (mixotrophs)  Nutritional modes help explain the roles in the ecosystem 1. photosynthetic (algae) 2. ingestive or animal like (protozoan) 3. absorptive (fungus like)  Most are aquatic inhabiting both marine and freshwater  Reproduce both asexually and through meiosis

Endosymbiosis  The diversity of protists can be attributed to the theory where unicellular organisms engulfed other cells and formed a symbiotic relationship with the host cell or the Endosymbiotic theory -evidence is shown by the origin of mitochondria -double membrane; own DNA; able to reproduce on its own

Diplomonads & Parabasalids  Generally both lack plastids (cholorplast); mitochondria lack DNA  Found in Anaerobic environments Diplomonads - two nuclei and multiple flagella Ex: Giardia intestinalis – parasite found in drinking water contaminated with feces - cause severe diaherra - can be killed by boiling water Parabasalids trichomonads – Trichomonas vaginalis - found in reproductive tract of female - infects the mucous lining - can occur in males - horizontal gene transfer changed parabasalids to pathogenic form

Euglenozoans  Main feature of this group is the spiral or crystalline rod inside the flagella Kinetoplastids - single mitochondrion with organized mass of DNA(kinetoplast) - free living consumer Ex: Trypanosoma – spread by tsetse fly causes sleeping sickness; can change surface proteins to avoid detection by immune system; can be fatal Euglenids - pocket at one end with one or two flagella - autotrophic, but capable of being heterotrophic when light is unavailable Ex: Euglena

Alveolates  Emerging SAR clade from molecular systematics  Characterized by membrane bound sac (alveoli) beneath plasma membrane - function is believed to regulate cell’s water and ion content or stabilize the surface Three groups Dinoflagellates Apicomplexans Ciliates

Alveolates Dinoflagellates - components of phytoplankton - unicellular or colonial - Red tide – explosive population growth (blooms) that produce toxins can be fatal to invertebrates and fish, even humans - Bioluminenscent – may be a defense mechanism to attact larger predators to eat the organisms that feed on dinoflagellates

Alveolates Apicomplexans -parasites of animals (require host) -spread by infectious cells called sporozoites -apex contains a complex of organelles that are specialized for penetrating host cells -not photosynthetic - apicoplast synthesizes fatty acids -both sexual and asexual cycles that may require two or more host species Ex: Plasmodium – causes malaria

Alveolates

Ciliates - cilia surrounds entire organism - generally asexual, but do carry out conjugation - distinctive feature is two types of nuclei - macronuclei – contains copies of genome; carries out daily functions : feeding, waste removal, and water balance - micronuclei – may be transferred during conjugation; develop into macronuclei Ex: paramecium

Stramenopiles General characteristics  Most are heterotrophs  Flagellum contains tiny fine hairs but also smooth hairless extensions Members of group - Oomycetes - Diatoms - Golden Algae - Brown Algae

Stramenopiles Oomycetes – water molds, white rusts, mildews - fungus like relation as a result of convergent evolution, but are not fungi - cell wall made of cellulose rather than chitin - flagellated cells - multinucleated hyphae (branches) - no plastids and no longer carry out photosynthesis - acquire nutrients as parasites or decomposers Ex: Phytophthora infestans – causes potato late blight (turns stalk and stem of potato crops to black slime) - Irish potato famine in 19 th century; - Still occurs to 15% of North American potatoes - also has become more aggressive and resistant to pesticides

Oomycetes

Stramenopiles Diatoms - unicellular algae - glass like wall of hydrated silica embedded in organic matrix - reproduce asexually where half cell wall comes from parent other half is generated on their own - component of phytoplankton - store food source in glucose polymer laminarin - used in nanotechnology

Stramenopiles Golden algae - named for color contributed by yellow and brown carotenoids - contain 2 flagella at the end of cell - components of marine and freshwater plankton - photosynthetic - unicellular and colonial species possible Brown Algae - largest and most complex algae - multicellular and marine - commonly known as seaweeds - resemble plants but lacks true roots, stems, and leaves - common uses ingredient in soups, thickener in pudding, ice creams, and salad dressing Ex: kelp

Cercozoans  Newly recognized clade Rhizarians that is type of amoeba  Move and feed by means of pseudopodia which are extensions that may bulge from cell surface  Designated by threadlike pseudopodia  Inhabit marine, freshwater and soil  Many are parasites, but others also predators  Autotrophic cercozoans possible -Ex: Paulinella chromatophora

Rhizarians Foraminiferans (Forams) - Porous shells called tests - tests can be multi-chambered and hardened with calcium carbonate - derive nourishment from the photosynthesis of symbiotic algae - inhabit fresh and marine water Radiolarians - marine protists - tests made of silica - pseudopodia radiates from center of body(axopodia)

Amoebozoans  Amoebas with lobe shaped pseudopodia Gymnamoebas - unicellular found in soil or water - heterotrophs that feed on bacteria and other amoebas; detritus eaters Entamoebas -parasites that infect all classes of vertebrates - Entamoeba histolytica – pathogenic, causing dysentery; multiple deaths worldwide

Amoebozoans Plasmodial slime molds - bright pigments - form plasmodium – large cytoplasmic mass undivided by membranes *accomplished by mitosis without cytokinesis - live in moist soil, leaf mulch, rotting logs - haploid and diploid life cycle - fruiting bodies that are stalked; form when conditions are harsh (sexually reproduce)

Amoebozoans Cellular slime molds - mainly solitary, but under depleted conditions can form colonies (separated by membranes) - mostly haploid life cycle - fruiting bodies are asexual - no flagellated stages

Red and Green Algae Red algae -reddish pigment called phycoerythrin - species color can depend on depth in water - inhabit warm coastal or tropic water - multicellular - alteration of generations - can be designated as seaweeds Ex: dulce – common edible seaweed

Green and Red Algae Green Algae- Volvox, Spirogyra - much like plants - divided into chlorophytes and charophyceans - mostly freshwater inhabitants - can live symbiotically with fungi, other eukaryotes -evolved into larger more complex organisms by: 1. formation of colonies of individual cells 2. repeated division of nuclei without cytokinesis 3. formation of true multicellular forms - mainly sexual reproducing; possible alterations of generations