Protists First discovered by Leeuewenhoek after discovery of microscope- called “animalcules”...
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Transcript of Protists First discovered by Leeuewenhoek after discovery of microscope- called “animalcules”...
Protists•First discovered by Leeuewenhoek after discovery of microscope- called “animalcules”
•All eukaryotes, mostly single celled, some multi-cellular but no specialized tissues
Kingdom Protista vs. “protists”•Classification of Protista and protists in flux
•Traditionally, Kingdom Protista is all eukaryotes that are not plant, animal or fungi (the misfits)
•Most diverse kingdom; many members resemble other kingdoms more than they do each other
•Group does not adhere to cladistics
•The term “protists” may refer to organisms no longer considered in the Kingdom Protista
5 Eukaryotic Supergroups: a phylogenetic hypothesis
•Attempt to arrange protists into true clades
•Based on molecular and/or structural evidence
•Plants, Animals, Fungi included
•Protists in yellow
•Dotted lines indicate uncertain relationships
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Why do we care about protists?•Autotrophic protists produce over 75% of our atmospheric oxygen
•Decomposer protists play an important role in eating dead organic matter and recycling materials in our ecosystem
•Certain kinds cause “red tide” and lead to build up of toxins in shellfish (can poison man; kill aquatic life)
•When certain inorganic nutrients are high, can cause bloom of protists; they multiply and cover top of water so no light penetrates and aquatic plants and animals die leading to eutrophication
Based on your microscopy observations a couple of weeks ago, how would you classify
protists?
nutritionautotrophs
heterotrophsmixotrophs
movementflagella
ciliapseudopodsnon-motile
other kingdom most likeanimal-likeplant-like
fungus-like
Here is how we will go through protists:
•Animal-like •Flagellates •Pseudopods •Ciliates •Sporozoa•Plant-like•Euglenoids•Dinoflagellates•Diatoms•Fungus-like•slime molds
Animal-like protists
•also called protozoans•heterotrophs
Animal-like protists: Flagellates
•many parasitize man•have long whiplike flagella used to move
•reproduce both sexually and asexually
Animal-like protists: Flagellates
Trypanosomes*
African sleeping sickness; South American Chagas disease
Animal-like protists: Flagellates
Trypanosomes* Nutrition: obligate parasite
Locomotion: single flagella and an undulating membrane
Protective adaptations: Change their surface antigens to avoid the host’s immune system. The change occurs usually at 3-week intervals, just when antibody is produced to the old antigen.
Other unusual characteristics: Sleeping sickness spread tse-tse fly. Chagas disease is can lead to congestive heart failure. These are zoonotic infections (transferred from animal to animal using a vector). Have a single large mitochondria with a mass of DNA called a kinetoplast.
Kingdom or Phylum: Kingdom Protista, Phylum Euglenozoa, Class Kinetoplastea
Animal-like protists: Flagellates
Trychonympha
Live in the guts of termites; make enzymes that digest cellulose for the termite; symbiotic relationship
Animal-like protists: Flagellates
Trichomonas vaginalis*
Causes sexually transmitted disease
Animal-like protists: Flagellates
Trichomonas vaginalis*
Nutrition: parasite; causes STD
Locomotion: multiple flagellae
Protective adaptations: Anaerobic.
Other unusual characteristics: No DNA and no electron transport chain in the mitochondria. 2 equal-sized nuclei.
Kingdom or Phylum: Kingdom Protista, Phylum or Clad Diplomonadida; some put in Kingdom Archezoa since lacks true mitochondria
Animal-like protists: Flagellates
Giardia
Anaerobic; intestinal parasite; spread through fecal-oral route by drinking contaminated food or water; big concern for campers using water sources near beaver dams
Animal-like protists: Pseudopods
•amoeba-like movement•eat by phagocytosis (contain actin + myosin)
•some responsible for human disease
•foraminifera and radiolarians are “shelled” amoeba
•radiolarians comprise “chert”- sedimentary rock made of silica
Animal-like protists: Pseudopods
Pelomyxa* Nutrition: heterotroph, takes in food by phagocytosis, eat protozoa and invertebrates
Locomotion: pseudopodia
Protective adaptations: Habitat is in freshwater mud. Tolerate very low levels of oxygen almost to point of being anaerobic.
Other unusual characteristics: Contain methanogenic bacteria that live in symbiotic relationship. Provide energy in place of mitochondria. Multinucleate and nuclei all divide together.
Kingdom or Phylum: Kingdom Protista or Kingdom Archezoa (due to no mitochondria); Phylum Amoebozoa
Animal-like protists: Pseudopods
Amoeba proteus*
Nutrition: heterotroph
Locomotion: pseudopods
Protective adaptations:
Other unusual characteristics: Can sense light and tends to move away from it. Just before it reproduces, it rounds up into a ball with tiny pseudopodia extensions. Over the next 15 minuts or so, it splits and becomes 2.
Kingdom or Phylum: Kingdom Protista, Clad Amoebozoa
Animal-like protists: PseudopodsEntameoba histolytica*
Nutrition: obligate parasite
Locomotion: pseudopod
Protective adaptations: can form cysts for survival during harsh conditions
Other unusual characteristics: passed by oral-fecal route; adheres to host lumen, can bore into intestinal wall, can cause amoebic dysentery and amoebic liver, lung or brain abscess; anaerobic; lack mitochondria
Kingdom or Phylum: Kingdom Archezoa
Animal-like protists: Pseudopods
Actinosphaerium*
Animal-like protists: Pseudopods
Actinosphaerium* Nutrition: heterotrophs feeding on small flagellates and ciliates and microscopic algae
Locomotion: pseudopodia supported by axopods radiating outward from the cell body, which adhere to passing prey and allow it to roll or float about
Protective adaptations: form a cyst, which is multi-walled and covered in spikes
Other unusual characteristics: fresh water; frequent in lakes and rivers; few found in marine and soil habitats; unicellular and roughly spherical in shape; called “heliozoan” or “sun animal”
Kingdom or Phylum: Kingdom Chromista; Protist kingdom: Phylum Cercozoae
Animal-like protists: Pseudopods
Foraminifera “shelled amoeba”
shell called a “test”
some secrete calcium carbonate shells
the foraminifera shells make up the limestone used to build the pyramids in Egypt
Animal-like protists: Pseudopods
Radiolarians
“shelled amoeba”
comprise “chert”- sedimentary rock made of silica
shell called a “test”; shell has pores that pseudopodia stick out of.
Animal-like protists: Ciliates•complex sub-cellular organization, form
vacuoles•contain oral groove and pellicle (protein layer beneath plasma membrane)
•2 nuclei types: Micro (diploid; divides by meiosis, involved in reproduction, forms macro) and macro (polyploid; nucleus which carries out cell’s functions)
•reproduction is asexual (the macro nucleus divides by splitting in half) and sexual (haploid micronuclei from meiosis exchanged by conjugation)
•contain trichocysts (used as tentacles to capture prey and as an anchor to attach to a surface)
Animal-like protists: Ciliates
Paramecium*
Animal-like protists: Ciliates
Paramecium* Nutrition: heterotroph; cilia line oral groove, food moves into pharynx, egest through the anal pore, eat protists and yeast
Locomotion: thousands of cilia, cellular extensions that extend through the pellicle
Protective adaptations: trichocysts reach surface through pores in the pellicle, can be discharged into fine threads; contractile vacuoles for water balance
Other unusual characteristics: live in fresh water, covered by a stiff, flexible pellicle, rounded front and pointed end, can regenerate if small piece of the nucleus is contained in the cut piece, two types of nuclei- macro and micro; reproduce by binary fission (asexual) and conjugation (sexual)
Kingdom or Phylum: Kingdom Protista, Clad Alveolata (membrane bound sacs under plasma membrane that look like alveoli in the lungs)
Animal-like protists: Ciliates
Stentor* Nutrition: heterotroph
Locomotion: cilia and circlet of membranes; heterotrichs because they have different cilial structures on different parts of body
Protective adaptations: lengthwise contractile fibers (myonemes similar to the Vorticella) that shorten the body
Other unusual characteristics: attaches when feeding; large nucleus resembling a string of beads and many small nuclei; amazing powers to regenerate even from a small portion of the cell; primary photosensor is called stentorin
Kingdom or Phylum: Same as Paramecium
Animal-like protists: Ciliates
Blepharisma*
Nutrition: heterotrophic filter feeders; eat bacteria found in decaying vegetation
Locomotion: move by cilia just like paramecium
Protective adaptations: photophobic; contain photosensory pigments in the pellicle located in pigment granules called blepharismins
Other unusual characteristics: pale pink to bright red with pigmentation granules; have undulating membrane and a single contractile vacuole with no canals
Kingdom or Phylum: same as Paramecium
Animal-like protists: CiliatesVorticella*
Nutrition: heterotroph; feeds mainly on bacteria
Locomotion: cilia around the broad end of the bell shaped body
Protective adaptations: can release the stalk and move to another location if needed; will regenerate the stalk; inside fibers of the stalk are myonemes that contract when disturbed
Other unusual characteristics: attach to substrate by the stalk; asexual reproduction by dividing lengthwise; also sexual by conjugation
Kingdom or Phylum: same as Paramecium
Animal-like protists: Sporozoa
•Apicomplexans (named for apical structure that helps parasite enter host cell)
•spore forming•internal parasites•alternation between haploid and diploid forms
•immobile
Animal-like protists: Sporozoa
Plasmodium* Nutrition: obligate parasite
Locomotion: no known method
Protective adaptations: apex contains complex of organelles used to penetrate the host cell
Other unusual characteristics: non-photosynthetic plastid or apicoplastid believed to originate from a chloroplast so these may have once been photosynthetic; transferred by the bite of the female Anopheles mosquitos; cause malaria
Kingdom or Phylum: Kingdom Protista; Phylum or clad Diplomonadida; some put in Kingdom Archezoa since it lacks mitochondria
Animal-like protists: Sporozoa
Plasmodium*
Plant-like protists: Euglenoidea
Euglena* Nutrition: photosynthetic or mixotrophs; can absorb nutrients through the cell membrane; storage molecule is paramylon
Locomotion: pocket at one end where 2 flagella come from; has euglenoid movement
Protective adaptations: one contractile vacuole for water balance; contains an eyespot or stigma that is light sensitive (positive phototropism)
Other unusual characteristics: flagellate protozoa; all protozoa are photosynthetic flagellates; has an elastic pellicle
Kingdom or Phylum: Kingdom Protista; Clad Euglenozoa; Euglenids
Plant-like protists: Dinoflagellates
Dinoflagellates*
Plant-like protists: DinoflagellatesDinoflagellates*
Nutrition: marine and freshwater phytoplankton so they are photosynthetic (contain chlorophylls); some heterotrophs
Locomotion: 2 flagella located in a groove; protective cellulose plates cover dinoflagellates
Protective adaptations: contain carotenoids; produce toxins eaten by mollusks and then humans; some cause Red Tide
Other unusual characteristics: cause red tide (contain carotenoids); main food source for the coral reefs; bioluminescence
Kingdom or Phylum: Kingdom Protista; Phylum Alveolata; Dinoflagellates
Plant-like protists: DiatomsDiatoms
•reproduce by binary fission•produce shells or “tests”•lack flagella•produce diatomaceous earth used commercially as filtering agents or abrasives
Fungus-like protists•slime molds•live on damp soil, logs, decaying matter•saprophytes- heterotrophs that obtain food by eating detritis
•life cycle- alternation of generation between plasmodium (vegetative) stage and fruiting body (spore-forming) stage
•plasmodium stage is multinucleate and forms long hyphae; this gives high surface area to volume ratio which makes for more efficient exchange/absorption of nutrients and materials across the cell membrane
Fungus-like protists: slime molds
REVIEW
Read CH. 28 on Protists in Campbell & Reece
zoonotic infection: infectious disease that can be transmitted from animals to humans and vice versa by a vector
vector: organism that does not cause disease but transmits disease by conveying pathogens from one host to another
Terminology
Trypanosomes, obligate parasites, are pathogens in...
African sleeping sickness•transmitted by bite of tse tse fly•affects multiple organ systems finally crossing blood-brain barrier to give classic “sleeping” symptoms
South American Chagas disease•transmitted by bite of blood-sucking assassin bug•early on symptoms mild; over years leads to intestinal malformations and heart failure
Malaria•caused by protozoan obligate parasite Plasmodium (an Apicocomplexans)•transmitted by bite of female Anopheles mosquito•infects blood and liver cells in human•part of life cycle in mosquito; part in human
250 million fevers, 1 million deaths annually
Malarial pathogen: The Life Cycle of Plasmodium
Sporozoite
Red Tide: Dinoflagellates
•nutrient imbalance can lead to bloom (overpopulation) of dinoflagellates leading to Red Tide•dinoflagellates produce neurotoxin that kills fish and accumulates in filter feeders like shell fish•affects food supply as fish die and shell fish become toxic to eat
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