Protist outline-- CHAPTER 20 PROTISTS COMMON EXAMPLES: Amoeba, paramecium, euglena, volvox, plasmodium EUKARYOTIC Have a nuclear membrane VERY DIVERSE GROUP most are unicellular, microscopic, aerobic Some are autotrophic, heterotrophic, sexual, asexual PROTISTS ENDOSYMBIONT THEORY Early eukaryotes developed symbiotic relationships with prokaryotic cells Prokaryotic cells lived inside eukaryotic cells Over time, the smaller prokaryotic cells evolved with the eukaryotic cells to become mitochondria and chloroplasts EXCRETION AND OSMOREGULATION Water balance = osmoregulation Done by contractile vacuole Wastes removed by diffusion RESPIRATION Carbon dioxide and oxygen diffuse in and out REPRODUCTION Asexual Mitosis and cytokinesis Budding – similar to mitosis except daughter cell is smaller than parent Schizogony – nucleus divides many times and cytoplasm divides to form many daughter cells as there are nuclei SEXUALLY Meiosis – special nuclear division to reduce chromosome number to haploid Union of gametes = diploid zygote Syngamy – fertilization between two individuals Autogamy – two gametes fuse within one organism Parthenogenesis – development of organism from gamete without fertilization Conjugation – exchange of nuclear material between two individuals DOMAIN EUKARYOTA KINGDOM PROTISTA Any eukaryote that is not classified as a fungus, plant, or animal is a PROTIST ANIMAL LIKE PROTISTS = PROTOZOA Classified by method of movement PLANT LIKE PROTISTS = ALGAE Classified by pigment color FUNGUS LIKE PROTISTS = MOLDS Classified by body form PROTIST CLASSFICATION Separated by feeding habits (nutrition) Autotrophic Able to make own food Photosynthetic – 30-40% of all photosynthesis worldwide is done by algae Heterotrophic
Must eat other material Unicellular May be predators, decomposers, or parasites ANIMAL LIKE PROTISTS--PROTOZOA Heterotrophic Unicellular 4 groups Sarcodinians Zooflagellates Ciliophorans Sporozoans PHYLUM SARCODINA (sarcodinians/sarcodines) Aquatic, clear cytoplasm, irregular shape Move by extending lobes of their cytoplasm Pseudopods (false feet) Plasmolemma – elastic cell membrane Cytoplasm is divided into ectoplasm and endoplasm Nucleus, contractile vacuole, food vacuole Example: Amoeba proteus LABEL THIS AMEOBA (in book p. 500)
PHYLUM ZOOMASTIGINA (zooflagellates) Often called flagellates because they move using flagella Absorb food by diffusion through cell membrane Live off of dead or decaying organic matter or some are parasites Trichonympha lives in the gut of termites (helps termite digest wood) Trypanosoma – parasite of humans in Africa PHYLUM CILIOPHORA (ciliates) Ciliates – found in fresh and salt water; usually free-living, most are larger than other protozoa Pellicle, cilia, ectoplasm, endoplasm, food vacuole, contractile vacuole Micronucleus (exchanged during conjugation) Macronucleus (controls daily functions) TRICHOCYSTS – spindle shaped alternating between bases of cilia; used as anchor and to paralyze prey Oral groove – shallow furrow on one side of cell used to gather food Locomotion – cilia; avoiding reaction contact with unfavorable conditions and will move away Reacts to contact, temperature, gravity, water currents, electric currents, acidity and other chemicals Reproduction (p 502 FIG 20-6 in book) Mitosis every 6-12 hours
Conjugation – become sticky and adhere to each other at oral groove and exchange nuclear material (does not use pili like bacteria)
Example = paramecium (book p. 501) PHYLUM SPOROZOA (sporozoans) Members cannot move Reproduce by producing spores All endoparasites Have apical complexes (structures that aid in penetration of host cells or tissues) Example: Plasmodium – causes malaria; carried by vector (female Anopheles mosquito)
(also, book p 503)
PLANT LIKE PROTISTS (-phyte or -phyta means plant) Most perform photosynthesis Contain chlorophyll in chloroplast and possibly other pigments Divided into groups by pigment color PHYLUM EUGLENOPHYTA PHYLUM DINOFLAGELLATA PHYLUM HETEROKONTOPHYTA PHYLUM CHLOROPHYTA— Asexual and Sexual reproduction—book p 513 FIG 20-17 Alternation of generations Life cycle--p 514 FIG 20-18
PHYLUM EUGLENOPHYTA Usually free-living (not a parasite) Pellicle – covering membrane; maintains shape Ectoplasm, endoplasm Cell mouth, gullet, reservoir (holds flagella), contractile vacuole, food vacuole Stigma (eyespot) - light sensitive Nucleus, chloroplasts Movement toward light using flagella; flagella pulls cell; euglenoid movement expansion and contractions of entire cell Nutrition – can capture food; can absorb nutrients from water or carry on photosynthesis Reproduction – mitosis; form cyst during harsh times Example: euglena; volvox
(also FIG 20-10 p. 507 in book) PHYLUM CHLOROPHYTA - GREEN ALGAE Contain chlorophyll b is their main type (which is very similar to land plants) Some reproduce sexually Examples: desmids, spirogyra Most live in fresh water or moist soil Many live in symbiotic relationships Lichen – organism composed of an algae and a fungi living together as one PHYLUM HETEROKONTOPHYTA Red algae, brown algae, golden algae RED ALGAE Grow in warm salt water habitats – toward surface or deep water Perform photosynthesis Example: Red moss BROWN ALGAE Multicellular and live in cool salt water habitats Includes giant kelps Have an alternation of generations life cycle (means that part of life is spent reproducing asexually and part is spent reproducing sexually) Used to make a variety of products As a thickening agent in puddings, ice cream Used as food for animals (processed) GOLDEN ALGAE – Some species are colorless, but the vast majority are photosynthetic. particularly important in lakes, where they may be the primary source of food for zooplankton. not considered truly autotrophic because nearly all become heterotrophic in the absence of adequate light, or in the presence of plentiful dissolved food. EXAMPLES - DIATOMS PROTISTS PHYLUM DINOFLAGELLATA (termed Pyrrophyta in your book) Nearly all have flagella
Most grow in salt water Most are free-living (meaning they are not parasites); some have symbiotic relationships with other organisms When agitated undergo reaction that produces light bioluminescent DINOFLAGELLATE Cause the red tide Several microscopic marine algae are notoriously poisonous to hapless humans who consume them in shellfish. some species are poisonous to animals which feed upon them directly or indirectly. Some of the toxins these species produce are seriously toxic. Often, the algae themselves are unaffected, as are the filter feeders, especially shellfish, for whom micro-algae are the principal diet. However, to carnivores further up the food chain, including humans, these toxins are potentially FATAL. PROTISTS FUNGUS-LIKE PROTISTS (MOLDS) CHARACTERISTICS MOST ARE SMALL AND LIVE IN DAMP PLACES PROTISTS THAT ACT AS DECOMPOSERS ARE CALLED MOLDS DIVIDED INTO 3 GROUPS PLASMODIAL (acellular) SLIME MOLDS CELLULAR SLIME MOLDS WATER MOLDS PLASMODIAL (acellular)SLIME MOLDS—Life cycle -- p 518 FIG 20-23in book Can weigh as much as 50 grams and be as large as a human hand (one cell!) Single cell with many nuclei In unfavorable conditions Moves somewhere else Creates a fruiting body Myxomycota - plasmodium CELLULAR SLIME MOLDS—Life cycle --p 517 FIG 20-22 in book ALTERNATES BETWEEN A SPORE PRODUCING FRUITING BODY FORM AND AN AMEBALIKE FEEDING FORM SINGLE CELLS UNITE TO FORM ONE LARGE MASS (PSEUDOPLASMODIUM) WHEN TIMES ARE HARSH WATER MOLDS—Life cycle --p 519 FIG 20-24 in book DECOMPOSERS IN FRESHWATER ECOSYSTEMS SOME ARE PARASITIC—potato famine in Ireland PROTISTS---IMPORTANCE OF PROTISTS ECOLOGICAL ROLES Provide an essential food base in aquatic food chains Carry out more than 30-40% of Earth’s photosynthesis Protozoans help keep the number of bacteria in check
