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Protists

Protists. Kingdom Protista (The hodge-podge Kingdom). Section 20-1 Kingdom Protista Protist = any organism that is not a plant, animal, fungus, or prokaryote

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Protists

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  1. Protists Kingdom Protista (The hodge-podge Kingdom)

  2. Section 20-1Kingdom Protista Protist = any organism that is not a plant, animal, fungus, or prokaryote - this kingdom is mostly unicellular, but includes many multicellular organisms as well - this kingdom will be broken into several kingdoms based on DNA analysis and other factors - similar to the first eukaryotes Classification of the Protists is based on Nutrition A) heterotrophic = animallike protists = protozoa B) autotrophic = plantlike protists C) decomposers/parasites = funguslike protists

  3. Endosymbiont Hypothesis – Lynn Margulis - hypothesis that explains the evolution of the first eukaryotic cells from symbiotic prokaryotes

  4. Animallike Protists = Protozoans - Unicellular heterotrophs - Four phyla based on locomotion: a. Zoomastigina – swim using flagella b. Sarcodina – move with pseudopodia c. Ciliophora – swim with cilia d. Sporozoa – no locomotion B. C. D. A.

  5. Zoomastigina = Zooflagellates - most have one or two flagella - most absorb nutrients through cell membrane - often decomposers or parasites - reproduce primarily by mitosis - Trypanosomes – African Sleeping Sickness - Trichomonas vaginalis – most common protozoan infection in humans

  6. Phylum Sarcodina – Sarcodines - move and feed via pseudopods - temporary cytoplasmic extensions - ameboid movement - surround and engulf food into food vacuoles, digested nutrients are used, and undigested materials exit through the cell membrane - reproduce by mitosis and cytokinesis - Amoebas are best known examples - Foraminiferans - sarcodines of warm oceans with calcium carbonate shells - White Cliffs of Dover in England Heliozoans

  7. Ameba Feeding with Pseudopods

  8. Phylum Ciliophora – Ciliates - use cilia for locomotion and feeding - very fast swimmers - live in both fresh and salt water - most are free-living Internal Structures of Paramecium - trichocysts – small defensive structures - macronucleus – controls normal activities - micronucleus – reserve copy of genes; exchanged during conjugation - gullet – oral groove into which food enters - food vacuoles form around food and lysosomes fuse with it to digest food - wastes exit through anal pore - contractile vacuoles keep water balance

  9. Paramecium Anatomy

  10. Paramecium Conjugation - normally paramecia reproduce by mitosis and cytokinesis - during stressful times they sometimes undergo conjugation - exchange micronuclei with each other - not reproduction because no new cells are formed, but it helps produce and maintain genetic diversity

  11. Phylum Sporozoa – Sporozoans - do not move on their own - parasitic - often have complex life cycles with more than one host - reproduce by means of sporozoites Animallike Protists and Disease 1. Malaria - Plasmodium parasite kills up to 2 million people per year - Female Anopheles mosquitoes are the vector - mosquito’s saliva enters a person with sporozoites which get in person’s blood

  12. - sporozoites enter liver and red blood cells - when erythrocytes burst it causes severe chills and fever - many strains of malaria have evolved resistance to the drugs we use against the parasites - best control is to control mosquitoes sporozoites sporozoites merozoites male gametophyte in erythrocyte

  13. 2. African Sleeping Sickness - Zooflagellate Trypanosoma - spread by Tsetse flies - damage the nervous system and can cause death 3. Amebic Dysentery - causes severe diarrhea and intestinal bleeding - Entamoeba - spreads by contaminated drinking water 4. Giardia - a flagellated protozoan that also causes diarrhea and digestive system problems Ecologically many protists are important decomposers and symbionts with other organisms - Trichonympha in termite guts digest cellulose

  14. Sec. 20 -3 Plantlike Protists – Unicellular Algae - often classified based on the type of photosynthetic pigments they have - have many different pigments to absorb the light that can penetrate into deep water (blue) - have chlorophyll a, b, and c - accessory pigments absorb wavelengths that chlorophylls can’t Phylum Euglenophyta - have two flagella, but no cell walls - genus Euglena - found in lakes and ponds - eyespot allows them to swim toward light - can live autotrophically or heterotrophically

  15. Phylum Chrysophyta – Yellow-green + golden-brown - means “golden plants” - cell walls of pectin rather than cellulose - golden algae often cause fish kills Lake Wichita Spring 2009

  16. Phylum Bacillariophyta – Diatoms - make shells of silicon (glass) - shells of two parts like a petri dish

  17. Phylum Pyrrophyta – Dinoflagellates - half are heterotrophic; half autotrophic - most have two flagella and a shell of thick cellulose - many are luminescent - Pyrrophyta means “fire plants”

  18. Ecology of Unicellular Algae 1. Phytoplankton - small photosynthetic organisms in the ocean - perform about half of all photosynthesis on Earth - are the base of the food chain – all sea-life depends on these autotrophs 2. Algal Blooms - happen when excess nutrients are in water and algae grow very rapidly - when nutrients are used up and the algae die, their decomposition takes all of the oxygen out of the water which causes many other organisms to die - “Red tides” can make shellfish poisonous

  19. Plantlike Protists: Red, Brown, and Green Algae - these groups are mostly multicellular - most have cell walls and life cycles like plants Phylum Rhodophyta = Red Algae - can live at great depth (260 meters) due to their efficiency at harvesting light energy - contain chlorophyll a and reddish accessory pigments called phycobilins which absorb blue light - important in coral reefs

  20. Phylum Phaeophyta = Brown Algae - contain chlorophyll a and c and the accessory pigment fucoxanthin - largest and most complex algae - mostly marine and often in cool, shallow coastal water - Kelp forests on west coast of U.S. - Sargassum forms huge floating mats on the ocean - many have air-filled bladders that help them float

  21. Phylum Chlorophyta – Green Algae - ancestors of green plants - cellulose cell walls, contain chlorophyll a and b; and store food as starch - most are aquatic, but some live on moist land - both unicellular, colonial, and multicellular - Chlamydomonas - unicellular Ulva - multicellular Volvox colonies

  22. Zygote (cross-section) A thick-walled resistant zygote develops. Diploid Stage Meiosis and Germination Nuclear Fusion Haploid Stage Haploid cell (+ strain) Haploid cell (- strain) Mitosis ASEXUAL REPRODUCTION ASEXUAL REPRODUCTION Cytoplasmic Fusion More spores produced. More spores produced. SEXUAL REPRODUCTION + – + Gametes of different mating types meet. – Life cycle of a species of Chlamydomonas

  23. zygote sporophyte (2n) Diploid Stage Meiosis Fertilization Haploid Stage germinating spore (n) male gametes female gametes 10 cm gametophyte (n)

  24. Human Uses of Algae - algal chemicals are used to treat stomach ulcers, high blood pressure, arthritis, and other health problems - many foods contain algae or algal products - thickening agent in ice cream, salad dressing, puddings, and candy bars - industry uses algal chemicals to make plastics, waxes, deodorants, lubricants, even artificial wood - agar is used in biology labs to grow bacteria on

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