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Protists First discovered by Leeuewenhoek after discovery of microscope- called “animalcules” All eukaryotes, mostly single celled, some multi-cellular.

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Presentation on theme: "Protists First discovered by Leeuewenhoek after discovery of microscope- called “animalcules” All eukaryotes, mostly single celled, some multi-cellular."— Presentation transcript:



3 Protists First discovered by Leeuewenhoek after discovery of microscope- called “animalcules” All eukaryotes, mostly single celled, some multi-cellular but no specialized tissues

4 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 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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7 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

8 Based on your microscopy observations a couple of weeks ago, how would you classify protists?

9 nutrition autotrophs heterotrophs mixotrophs movement flagella cilia pseudopods non-motile other kingdom most like animal-like plant-like fungus-like

10 Here is how we will go through protists: Animal-like Flagellates Pseudopods Ciliates Sporozoa Plant-like Euglenoids Dinoflagellates Diatoms Fungus-like slime molds

11 Animal-like protists also called protozoans heterotrophs

12 Animal-like protists: Flagellates many parasitize man have long whiplike flagella used to move reproduce both sexually and asexually

13 Animal-like protists: Flagellates Trypanosomes* African sleeping sickness; South American Chagas disease

14 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

15 Animal-like protists: Flagellates Trychonympha Live in the guts of termites; make enzymes that digest cellulose for the termite; symbiotic relationship

16 Animal-like protists: Flagellates Trichomonas vaginalis* Causes sexually transmitted disease

17 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

18 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

19 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

20 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

21 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

22 Animal-like protists: Pseudopods Entameoba 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

23 Animal-like protists: Pseudopods Actinosphaerium*

24 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

25 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

26 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.

27 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)

28 Animal-like protists: Ciliates Paramecium*

29 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)

30 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

31 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

32 Animal-like protists: Ciliates Vorticella* 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

33 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

34 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

35 Animal-like protists: Sporozoa Plasmodium*

36 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

37 Plant-like protists: Dinoflagellates Dinoflagellates*

38 Plant-like protists: Dinoflagellates Dinoflagellates* 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

39 Plant-like protists: Diatoms Diatoms reproduce by binary fission produce shells or “tests” lack flagella produce diatomaceous earth used commercially as filtering agents or abrasives

40 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

41 Fungus-like protists: slime molds

42 REVIEW Read CH. 28 on Protists in Campbell & Reece

43 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

44 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

45 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

46 Malarial pathogen: The Life Cycle of Plasmodium Sporozoite

47 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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