Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 28 Protists

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: Living Small Protist is the informal name of the kingdom of mostly unicellular eukaryotes Advances in eukaryotic systematics have caused the classification of protists to change significantly; therefore Protista is no longer valid as a kingdom

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 28.1: Most eukaryotes are single-celled organisms Protists are eukaryotes and thus have organelles and are more complex than prokaryotes Most protists are unicellular, but there are some colonial and multicellular species

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Structural and Functional Diversity in Protists Protists exhibit more structural and functional diversity than any other group of eukaryotes Single-celled protists can be very complex, as all biological functions are carried out by organelles in each individual cell

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Protists can reproduce asexually or sexually, or by the sexual processes of meiosis and fertilization (syngamy) Protists, the most nutritionally diverse of all eukaryotes, include: – Photoautotrophs, which contain chloroplasts – Heterotrophs, which absorb organic molecules or ingest larger food particles – Mixotrophs, which combine photosynthesis and heterotrophic nutrition

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Endosymbiosis in Eukaryotic Evolution There is now considerable evidence that much protist diversity has its origins in endosymbiosis Mitochondria evolved by endosymbiosis of an aerobic prokaryote Plastids evolved by endosymbiosis of a photosynthetic cyanobacterium The plastid-bearing lineage of protists evolved into red algae and green algae On several occasions during eukaryotic evolution, red and green algae underwent secondary endosymbiosis, in which they were ingested by a heterotrophic eukaryote

Fig Cyanobacterium Heterotrophic eukaryote Over the course of evolution, this membrane was lost. Red alga Green alga Primary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis Plastid Dinoflagellates Apicomplexans Stramenopiles Plastid Euglenids Chlorarachniophytes Plastids evolved from gram - cyanobacterium

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Five Supergroups of Eukaryotes It is no longer thought that amitochondriates are the oldest lineage of eukaryotes One hypothesis divides all eukaryotes (including protists) into five supergroups

Fig a Green algae Amoebozoans Opisthokonts Alveolate s Stramenopiles Diplomonads Parabasalids Euglenozoans Dinoflagellates Apicomplexan s 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

Fig b Diplomonads Parabasalids Euglenozoans Excavata Giardia intestinalis crystaline rod inside flagella, kinetoplastids and Euglenids modified mitichondria anaerobic grooved body no plastids, multiple flagella made of flagellin, 2 nucloeli, parasitic and free living Giardia releases H, Trichomonas, STD Trichomonas vaginalis STD Trypanosoma Euglena Chaga's disease and Sleeping Sickness EXCAVATA "the excavates" Diplomonad Parabasalid Euglenid Kinetoplastid

Fig c Alveolates Stramenopiles Dinoflagellates Apicomplexans Ciliates Diatoms Golden algae Brown algae Oomycetes Chromalveolata DNA sequence how old they are alveoli under the plasma membrane 2 flagella, one covered with fine stiff hairs and the other one smooth Chromalveolates

Alveolates Dinoflagelates cells reinforced by cellulose plates 2 flagella in grooves marine and freshwater plankton auto, mixo and heterotrophic toxic "red tide" dino= whirl Apicomplexa parasites apex=tip modified plastid complex lifecycle, 2 or more hosts malaria "bad air" P. falciparium, P. vivax, P. malariae, P. ovale Ciliates cilia used for locomotion and feeding macro and micronucleus sexual reproduction by conjugation Paramecium nucleus apex mitochondria

Contractile vacuole Oral groove mouth micronucleus macronucleus cillia MEIOSIS HAPLOID DIPLOID MICRONUCLEAR FUSION DIPLOID four haploid nucleoli are produced in each one three of which desintegrate DNA exchange two micronuclei fuse into one micronucleus 3 rounds of mitosis 4 micronuclei become macronuclei 2 rounds of cytokinesis producing four daughter cells 1. compatible mates align side by side and partially fuse Feeding, water balance and waste removal Conjugation and Reproduction of Paramecium food vacuoles Key haploid (n) diploid (2n)

Stramenopiles (stramen= straw, pilos= hair) Diatoms glass like wall made of hydrated silica, 2 parts overlaping walls with lacework of holes and grooves asexual reproduction more common 100,000 species, very diverse stores energy in form of oil and glucose polymer laminarin fossilized= diatomaseous earth biological carbon pump= carbon cycle Golden Algae color due to carotenoids biflagellated at one end of the cell freshwater and marine plankton all photosynthetic and some mixotropic (phagocytosis) uni and multicellular protective cysts that may survive decades Brown Algae multicellular mostly marine "sea weed" carotenoids in plastids similarities with plants evolved independantly (analogous) gel-forming polysaccharides cushions the thali from waves polysaccharides also prevent drying when exposed to air algin (found in cell walls) used as thickening agent in foods hetero- or isomorphic alternation of generations flagellum outer container living cell blade stipe

Fig cm Haploid (n) Diploid (2n) Key Sporangia Sporophyte (2n) Zoospore MEIOSIS Female Gametophytes (n) Egg Male Sperm FERTILIZATION Zygote (2n) Developing sporophyte Mature female gemetophyte (n) 1. found in water just below the line of lowest tide located on surface of blade originate in sporangia half develop into males and the other half to females eggs secrete a chemical signal attracting sperm zygotes develop into sporophytes while attached to the remains of the female gametophyte holdfast Alternation of Generations

Oomycetes "egg fungus" water molds, white rusts and downy mildews convergent evolution *similarities with fungus: multicellular hyphae *differences: cell walls made of chitin no plastids decomposers and/or parasites water molds live in freshwater, rusts and mildews are plant parasites *potato late blight genetic engineering is passing resistant genes to domesticated crops

Fig Germ tube Cyst Hyphae ASEXUAL REPRODUCTION Zoospore (2n) Zoosporangium (2n) Oogonium Egg nucleus (n) Antheridial ♂ hypha with sperm nuclei (n) Zygote germination SEXUAL REPRODUCTION Zygotes (oospores) (2n) 1. zoospores germinate on a substrate hyphae develop sexual structures antheridia grows around the oogonium depositing the sperm using fertilization tubes dormant period in which the oogonium wall desintegrates zygote forms hypha Key Haploid (n) Diploid (2n) MEIOSIS FERTILIZATION Life Cycle of Oomycetes

Fig d Chlorarachniophytes Forams Radiolarians Rhizaria Rhizarians vary in morphology but very similar in molecular systematics referred as "amoebas" 2ry endosymbiosis with green algae plastid surrounded by 4 membranes vestigial nucleus called nucleomorph calcium carbonate shells silica shells threadlike pseudopods

Foraminifera foramen= hole ferre= to bear found in ocean and freshwater porous shell known as tests form the sedimentary rocks symbiotic algae pseudopodia shell made of CaCO 3

Radiolaria symmetrical internal skeleton made of silica pseudopodia reinforced by microtubules marine pseudopods

Fig e Red algae Chlorophytes Charophyceans Land plants Green algae Archaeplastida red and green algae, and land plants unicellular and multicellular species Archaeoplastida

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 28.5: Red algae and green algae are the closest relatives of land plants Over a billion years ago, a heterotrophic protist acquired a cyanobacterial endosymbiont The photosynthetic descendants of this ancient protist evolved into red algae and green algae Land plants are descended from the green algae Archaeplastida is a supergroup used by some scientists and includes red algae, green algae, and land plants

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Red algae are reddish in color due to an accessory pigment call phycoerythrin, which masks the green of chlorophyll The color varies from greenish-red in shallow water to dark red or almost black in deep water Red algae are usually multicellular; the largest are seaweeds Red algae are the most abundant large algae in coastal waters of the tropics

Fig Bonnemaisonia hamifera 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. Red Algae Rhodophytes rodo=red phycoerythrin masks chlorophyll in shallower waters= less phycoerythin may lack pigments, act as parasites tropical oceans, freshwater and terrestrial multicellular alternation of generation cycle no flagellated states in life cycle water currents bring gametes together

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Green algae are named for their grass-green chloroplasts Plants are descended from the green algae The two main groups are chlorophytes and charophyceans Most chlorophytes live in fresh water, although many are marine Other chlorophytes live in damp soil, as symbionts in lichens, or in snow Chlorophytes include unicellular, colonial, and multicellular forms Most chlorophytes have complex life cycles with both sexual and asexual reproductive stages

Fig Ulva, or sea lettuce Caulerpa, an intertidal chlorophyte 2 cm Chlamydomonas

Fig µm Flagella Cell wall Nucleus Cross section of cup-shaped chloroplast Mature cell (n) Zoospore ASEXUAL REPRODUCTION Haploid (n) Diploid (2n) Key Gamete (n) Zygote (2n) SEXUAL REPRODUCTION MEIOSIS FERTILIZATION + + – – 1. mature cell, contains single cup shaped chloroplast Chlamydomonas when environment declines gametes are developed gametes fused forming diploid zygote coat is secreted to protect zygote from harsh conditions after dormancy meiosis produces 4 haploid cells (n), 2 of each mating type (+/-) undergoes 2 rounds of mitosis emerging as zoospores (n) Life Cycle of Chlamydomonas

Fig f Choanoflagellates Animals Fungi Gymnamoebas Entamoebas Nucleariids Unikonta Slime molds Amoebozoans Opisthokonts Unikonta

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 28.6: Unikonts include protists that are closely related to fungi and animals The supergroup Unikonta "one flagella" includes animals, fungi, and some protists This group includes two clades: the amoebozoans and the opisthokonts (animals, fungi, and related protists) The root of the eukaryotic tree remains controversial It is unclear whether unikonts separated from other eukaryotes relatively early or late

Fig Common ancestor of all eukaryotes DHFR-TS gene fusion Unikonta Excavata Chromalveolata Rhizaria Archaeplastida Choanoflagellates Animals Fungi Amoebozoans Diplomonads Euglenozoans Alveolates Stramenopiles Rhizarians Red algae Green algae Plants Hypothesis about the Eukaryotic Tree

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Amoebozoans are amoeba that have lobe- or tube-shaped, rather than threadlike, pseudopodia They include gymnamoebas, entamoebas, and slime molds pseudopods engolfing a small green algae Amoeba proteus

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Slime Molds Slime molds, or mycetozoans, were once thought to be fungi Molecular systematics places slime molds in the clade Amoebozoa Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange Plasmodium is an example

Fig Feeding plasmodium Mature plasmodium (preparing to fruit) Young sporangium Mature sporangium Stalk 4 cm 1 mm Key Haploid (n) Diploid (2n) MEIOSIS Spores (n) Germinating spore Amoeboid cells (n) Flagellated cells (n) Zygote (2n) FERTILIZATION 1. feeding stage multinucleated lives on organic matter mature plasmodium takes a weblike form sporangia or fruiting bodies germination occurs in favorable conditions ameboid or flagellated stages can convert from one to the other repeated mitotic division w/o cytoplasmic division forms feeding plasmodium Life Cycle of Plasmodial Slime Mold

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cellular Slime Molds Form multicellular aggregates in which cells are separated by their membranes Cells feed individually, but can aggregate to form a fruiting body

Fig Spores (n) Emerging amoeba (n) 1.Solitary amoebas (n) Aggregated amoebas Migrating aggregate Fruiting bodies (n) ASEXUAL REPRODUCTION 600 µm 200 µm Key Haploid (n) Diploid (2n) Amoebas (n) Zygote (2n) SEXUAL REPRODUCTION MEIOSIS FERTILIZATION 2 fuse to form a zygote becomes a giant cell that eats other amoebas and develop thick wall the cell multiplies by meiosis and several mitosis events, rupturing and releasing the new haploid amoebas when food is scared amoebas congregate in responce to a chemical attraction forming a slug-like aggregate a stalk is formed supporting an asexual fruiting body. Some of the cells dry up by this time other cells crawl up the stalk and develop into spores in favorable conditions amoebas emerge Cellular Slime Mold Life Cycle

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Gymnamoebas (Gymno=naked) Gymnamoebas are common unicellular amoebozoans in soil as well as freshwater and marine environments Most gymnamoebas are heterotrophic and actively seek and consume bacteria and other protists

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Entamoebas are parasites of vertebrates and some invertebrates Entamoeba histolytica causes amebic dysentery in humans

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Opisthokonts opistho=posterior the flagella is located in the posterior of the cell Include animals, fungi, and several groups of protists these are more related to fungi than to the rest of protists, therefore will be seen in future chapters

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 28.7: Protists play key roles in ecological relationships Protists are found in diverse aquatic environments Protists often play the role of symbiont Some protist symbionts may benefit their hosts – Dinoflagellates nourish coral polyps that build reefs – Hypermastigotes digest cellulose in the gut of termites

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Some protists are parasitic – Plasmodium sp. causes malaria – Pfiesteria shumwayae is a dinoflagellate that causes fish kills

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Photosynthetic Protists ecological producers and consumers Many protists are important producers that obtain energy from the sun In aquatic environments, photosynthetic protists and prokaryotes are the main producers The availability of nutrients can affect the concentration of protists other consumers carnivorous plankton bacteria protistan producers herbivorous plankton soluble organic matter The End