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Prokaryotes and Protists
CH 16
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PROKARYOTES Prokaryotes have inhabited Earth for billions of years
Prokaryotes are the oldest life-forms and remain the most numerous and widespread organisms Colorized SEM 650 Figure 16.7
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First Cells RNA might have acted as templates for the formation of polypeptides Assisted in RNA replication Self-replication of RNA Self-replicating RNA acts as template on which poly- peptide forms. Polypeptide acts as primitive enzyme that aids RNA replication. RNA Polypeptide Membrane-enclosed molecular cooperatives may have preceded the first cells
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Membranes may have separated various aggregates of self-replicating molecules which could be acted on by natural selection LM 650 Membrane Polypeptide RNA Figure 16.6B, C
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Prokaryotes Small, relatively simple cells
Do not have a membrane-bound nucleus Figure 4.3B
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Branches of Prokaryote Evolution
Bacteria and Archaea Distinguished on the basis of nucleotide sequences and other molecular and cellular features
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Prokaryote Shapes Cocci Bacilli Spirochetes
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Structural Features Gram staining Gram + (purple) Gram – (pink)
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
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Structural Features Capsule Pili Flagella
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Growth & Reproduction Binary Fission Endospore
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Innards Lacks membrane bound organelles
Respiratory / photosynthetic membrane Small, circular genome Ribosomes
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Nourishment Phototrophs & Chemotrophs Autotrophs & Heterotrophs
Biofilms Energy source Light Chemical CO2 Photoautotrophs Chemoautotrophs Carbon source Photoheterotrophs Chemoheterotrophs Organic compounds
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Archea Extremes Extremophiles Halophiles Thermophiles Methanogens
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Bacteria Proteobacteria Chlamydias Spirochetes Gram-positive bacteria
Cyanobacteria
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Disease Exotoxins Endotoxins
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Bacteria Uses Biological weaponry Bioremediation
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Bioremediation Recycle chemicals and clean up the environment
Prokaryotes are decomposers in Sewage treatment and can clean up oil spills and toxic mine wastes Liquid wastes Outflow Rotating spray arm Rock bed coated with aerobic bacteria and fungi Is the use of organisms to clean up pollution Figure 16.16A, B
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Protists are an extremely diverse assortment of mostly unicellular eukaryotes
Colorized SEM 4,000 The parasitic Giardia Plasmodium causes malaria Red blood cell Apex TEM 26,000 Single celled algae SEM 2,300
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Protists and Evolution
Multicellularity evolved in several different lineages probably by specialization of the cells of colonial protists Unicellular protist Colony Early multicellular organism with specialized, interdepen- dent cells Later organism that produces gametes Food- synthesizing cells Locomotor cells Somatic cells Gamete 1 2 3
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Symbiosis Endosymbiosis Secondary endosymbiosis Green alga Remnant of
Nucleus Secondary endosymbiosis Chloroplast Euglenozoans Cyanobacterium Remnant of red alga Primary endosymbiosis Autotrophic eukaryotes Heterotrophic eukaryotes Example of symbiosis- jelly fish of salt water lakes in Palou Nucleus Dinoflagellates Heterotrophic eukaryote Evolved into chloroplast Secondary endosymbiosis Apicomplexans Nucleus Chloroplast Red alga Stramenopiles
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Protists Diplomanads Euglenozoans Alveolates Parabasalids
Dinoflagellates Ciliates Apicomplexans
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Protists Stramenopiles Amoebozoans Watermolds Diatoms Brown Algae
Feed via pseudopodia Plasmodial slime mold Plasmodium Cellular slime molds
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Protists Foraminiferans Radiolarians Algae Red Green
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