PHYLUM PROTISTA

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. photoautotrophsb. heterotrophsc. 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 environmentsDiplomonads

- two nuclei and multiple flagellaEx: 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 flagellaKinetoplastids

- 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 surfaceThree groups

DinoflagellatesApicomplexansCiliates

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

AlveolatesApicomplexans

-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

AlveolatesCiliates

- 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 macronucleiEx: paramecium

StramenopilesGeneral characteristics Most are heterotrophs Flagellum contains tiny fine hairs but

also smooth hairless extensionsMembers of group

- Oomycetes- Diatoms- Golden Algae- Brown Algae

StramenopilesOomycetes – 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 19th century; - Still occurs to 15% of North American potatoes

- also has become more aggressive and resistant to pesticides

Oomycetes

StramenopilesDiatoms

- 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

StramenopilesGolden 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 dressingEx: 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

RhizariansForaminiferans (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 waterRadiolarians- marine protists- tests made of silica- pseudopodia radiates from center of body(axopodia)

Amoebozoans Amoebas with lobe shaped pseudopodiaGymnamoebas

- unicellular found in soil or water- heterotrophs that feed on bacteria

and other amoebas; detritus eatersEntamoebas

-parasites that infect all classes of vertebrates

- Entamoeba histolytica – pathogenic, causing dysentery; multiple deaths

worldwide

AmoebozoansPlasmodial 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)

AmoebozoansCellular 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 AlgaeGreen 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 cells2. repeated division of nuclei without cytokinesis3. formation of true multicellular forms

- mainly sexual reproducing; possible alterations of generations