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Protists (Chapter 29)

Protists (Chapter 29). Endosymbiosis (29.1). Eukaryotes fossils date back to 2.7 bya but differences in cells are seen in microfossils approximately 1.5 bya Larger than prokaryotes with thick walls and internal membranes Eukaryotes (true nucleus).

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Protists (Chapter 29)

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  1. Protists (Chapter 29)

  2. Endosymbiosis (29.1) Eukaryotes fossils date back to 2.7 bya but differences in cells are seen in microfossils approximately 1.5 bya Larger than prokaryotes with thick walls and internal membranes Eukaryotes (true nucleus) Most scientists believe that prokaryotic cells lost their cell wall which allowed their membrane to infold. This infold allowed for formation of endoplasmic reticulum and nuclear membrane Bacteria was believed to have been engulfed by a larger cell that eventually evolved and became mitochondria How did Eukaryotic Cells evolve?

  3. http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/animation_-_endosymbiosis.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/animation_-_endosymbiosis.html Video on Endosymbiosis

  4. Photosynthetic Bacteria • Both Mitochondria and Chloroplasts contain their own DNA • Chloroplasts are believed to have derived from cyanobacteria

  5. Formation of Red and Brown Algae

  6. Mitosis • Mitosis did not evolve rapidly • Nuclei does not break open is some protists and fungus. • Mitosis stays within the nucleus • Nucleus will divide into two daughter nuclei • The cell will then undergo cell division

  7. Defining Protists (29.2) • Protists are a largely diverse group • They are classified as eukaryotes that are not fungi, plants or animals • Thus, they are sometimes considered plant-like, animal-like or fungal-like • Textbook groups 15 major protist phyla into 7 groups

  8. Protists Groups

  9. Cell Surface • Some protists have only cell membrane while other have an extracellular matrix (ECM) outside the cell membrane (diatoms with silica or formanifera) • Some protists form cysts to protect them from environmental conditions

  10. Locomotion • Protists vary in ways they move • Flagella • Pseuopodia (false feet) • Cilia • Filopodia • axopodia

  11. Nutrients • Protists can either be heterotrophs or autotrophs • Phototrophs – obtain energy through photosynthesis • Heterotrophs – obtain energy from organic molecules • Phagotrophs - use food vacuoles to ingest food particles • Lysosomes digest particles • Osmotrophs • Digest soluble particles • Mixotrophs – both heterotrophic and autotrophic

  12. ReproductionMost protists reproduce asexually while other can reproduce sexually Sexual Mitosis Slightly different from multicellular animals - smaller Budding Schizogony Several nuclear divisions Reproduction through fertilization Haploid to diploid Allows for frequent genetic recombination Asexual

  13. Multicellular • Protists can be unicellular or multicellular • Being multicellular has advantage of creating high diversity due to genetic mutations • Being multicellular aids in specialization of cells to perform certain functions

  14. Diplomonads and Parabasalids • Diplomonads • Unicellular • Flagella • Lack mitochondria • Two nuclei • Contaminated water causing diarrhea • Giardia intestinalis • Parabasalids • Symbiotic relationships • Trichomonastermopsidis • termite gut • Undulating membranes for movement

  15. Trichomonasvaginalis Giardia intestinalis

  16. Euglenozoa • Approximately 30% have chloroplasts – autotrophs • Others ingest food – heterotrophs • Size anywhere from 10 to 500 ųm • Pellicle – flexible • Reproduce via mitosis - asexual • Euglena • Two flagella – reservoir • Contractile vacuole • Regulate osmotic pressure • Stigma – move to light • Chloroplasts

  17. Euglenozoa (cont’d) • Kinetoplastids • Single mitochondria • Two types DNA • Minicircles and maxicircles • Parasitic • Trypanosomes • African Sleeping sickness • Leishmaniasis • Chagas

  18. Alveolota • Flattened vesicles • Alveoli stacked below cell membrane • Dinoflagellates • Photosynthetic • Unicellular • Two flagella • Marine and fresh water • Some bioluminesce • Outer plate of cellulose-like w/silica • Flagella - spin • Dinoflagellates can cause red tide – toxins • Asexual unless starvation occurs then sexual

  19. Dinoflagellates Red Tide

  20. Apicomplexan • Plasmodium – injected into bloodstream by mosquitos causing malaria • Working on vaccine • ToxoplasmicGondii • Attack cells in human stomach • Brain damage, heart or skeletal tissue damage • Harm unborn child through cat litter box

  21. Ciliates • Heterotrophic • Unicellular • Cilia • Pellicle (tough outer covering) • Micro and Macronucleus • Vacuoles • Conjugation

  22. Stramenopila (Fine Hairs) • Brown algae • Sporophyte and gametophyte life cycle • Sporophyte – meiosis producing spores then through mitosis • Kelps • multicellular • Do not contain xylem or other plant tissue • Diatoms • Chrysophyta phylum • Photosynthetic • Unicellular • Double shell – silica • Produce carbohydrate – chrysolaminarin • Some move using raphes

  23. Diatoms Kelp with spores

  24. Oomycetes • Water Mold • Parasitic or saprobes (eat dead organisms) • Previously classified fungi (-mycetes) • Motile spores (aka zoospores) that have flagella on opposite ends • Sexual reproduction with games and asexual reproduction with zoospores formation in sporangium • Irish Potato famish (Phytophtorainfestans)

  25. Water mold

  26. Rhodophyta (Red Algae) • Size varies in red algae from microscopic to 2m in length • Used to thicken foods such as ice cream • Lacks flagella and centrioles • Photosynthetic pigment – phycoerythrin, phycocyanin and allophyocyanin • Reproduce by: Alternation of generations

  27. Chanoflagellida • Similar to ancestor of sponges • One flagella • funnel shaped • Contractile collar of filaments • Eat bacteria by filtration

  28. Protists w/o Clades • Amoebas – Rhizopoda • Move by pseudopodia using actin and myosin (muscles) • Radiolarians – Actinopoda • Exoskeletons of silica • Shape exhibiting bilateral or radial symmetry

  29. Phylum Foraminifera • Heterotrophic • Marine • Pore-studded shells (tests) – CaCO3 • Vary in color and shell shape • Most ive in sand or attached to organisms • Podia for movement and gathering • Complex life cycle • White cliffs of Dover - oil

  30. Plasmodial Slime Molds • Slime molds once considered fungi • Plasmodial slime molds • Large plasmodium (feeding phase) • Single celled • Multinuclear • Orange, yellow or other color • food or moisture short supply migrates and forms sporangium to produce spores • Can last years if kept dry

  31. Cellular Slime Molds • Behave as separate amoebas • Moves in soil digesting bacteria • Scarce food – slug that moves

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