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Prokaryotes and Protists

Prokaryotes and Protists. CH 16. Colorized SEM 650 . PROKARYOTES. Prokaryotes have inhabited Earth for billions of years Prokaryotes are the oldest life-forms and remain the most numerous and widespread organisms. Figure 16.7. Self-replication of RNA. RNA.

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Prokaryotes and Protists

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  1. Prokaryotes and Protists CH 16

  2. Colorized SEM 650 PROKARYOTES Prokaryotes have inhabited Earth for billions of years • Prokaryotes are the oldest life-forms and remain the most numerous and widespread organisms Figure 16.7

  3. Self-replication of RNA RNA Self-replicating RNA acts astemplate on which poly-peptide forms. Polypeptide Polypeptide acts as primitive enzyme that aids RNA replication. First Cells • RNA might have acted as templates for the formation of polypeptides • Assisted in RNA replication

  4. Membrane RNA Polypeptide LM 650 Membranes may have separated various aggregates of self-replicating molecules which could be acted on by natural selection Figure 16.6B, C

  5. Prokaryotes Small, relatively simple cells • Do not have a membrane-bound nucleus Figure 4.3B

  6. Branches of Prokaryote Evolution Bacteria and Archaea • Distinguished on the basis of nucleotide sequences and other molecular and cellular features

  7. Prokaryote Shapes • Cocci • Bacilli • Spirochetes

  8. Structural Features • Gram staining • Cell wall differences • Gram + (purple) • Simple cell wall • Thick peptidogylcan layer • Gram – (pink) • More complex cell wall with lipids bonded to carbohydrates • Thin peptidoglycan layer

  9. Structural Features • Capsule • Pili • Flagella

  10. Growth & Reproduction • Binary Fission • Endospore

  11. Innards • Lacks membrane bound organelles • Respiratory / photosynthetic membrane • Small, circular genome • Ribosomes

  12. Nourishment • Phototrophs & Chemotrophs • Autotrophs & Heterotrophs • Biofilms Energy source Light Chemical CO2 Chemoautotrophs Photoautotrophs Carbon source Photoheterotrophs Chemoheterotrophs Organic compounds

  13. Archea Extremes • Extremophiles • Halophiles • Thermophiles • Methanogens

  14. Bacteria • Proteobacteria • Spirochetes • Gram-positive bacteria • Cyanobacteria

  15. Disease • Exotoxins • Endotoxins

  16. Bacteria Uses • Biological weaponry • Bioremediation

  17. Rotatingspray arm Rock bed coated withaerobicbacteriaand fungi Outflow Liquid wastes Bioremediation Recycle chemicals and clean up the environment • Prokaryotes are decomposers in • Sewage treatment and can clean up oil spills and toxic mine wastes Figure 16.16A, B

  18. Gamete Locomotorcells Somatic cells 2 3 1 Food-synthesizingcells Unicellular protist Colony Early multicellular organismwith specialized, interdepen-dent cells Later organism thatproduces gametes Protists and Evolution • Multicellularity evolved in several different lineages probably by specialization of the cells of colonial protists

  19. TEM 26,000 Apex Colorized SEM 4,000 SEM 2,300 Red blood cell • The parasitic Giardia Protists are an extremely diverse assortment of mostly unicellular eukaryotes Plasmodium causes malaria Single celled algae

  20. Symbiosis • Endosymbiosis • Secondary endosymbiosis Green alga Remnant of green alga Nucleus Secondary endosymbiosis Chloroplast Euglenozoans Cyanobacterium Remnant of red alga Primary endosymbiosis Autotrophic eukaryotes Heterotrophic eukaryotes Nucleus Dinoflagellates Heterotrophic eukaryote Evolved into chloroplast Secondary endosymbiosis Apicomplexans Nucleus Chloroplast Red alga Stramenopiles

  21. Protists • Diplomanads • Parabasalids • Euglenozoans • Alveolates • Dinoflagellates • Ciliates • Apicomplexans

  22. Protists • Stramenopiles • Watermolds • Diatoms • Brown Algae • Amoebozoans • Feed via pseudopodia • Plasmodial slime mold • Plasmodium • Cellular slime molds

  23. Protists • Foraminiferans • Radiolarians • Algae • Red • Green

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