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Evolutionary Advances in Organism Complexity

Explore the evolutionary transitions from prokaryotes to eukaryotes, unicellular to multicellular organisms, and haploid to diploid genomes. Understand the diverse life cycles, modes of reproduction, and advantages of varying organism sizes and lifespans.

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Evolutionary Advances in Organism Complexity

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  1. Bio. 230 --- Evolution II

  2. Evolutionary Advances (I) 1) CELL COMPLEXITYProkaryote ----------> Eukaryote  2) ORGANISM COMPLEXITYUnicellular ---> Colonial ---> Multicellular 3) ORGANISM SIZESmaller -------> Larger [?? ---------> Less Large]  4) ORGANISM LIFESPANShort --------> Longer [?? ----------> Shorter]  5) TYPE OF NUTRITIONHeterotrophic ----------> Autotrophic  6) GENOME CONTENT Haploid -------> Diploid 7) TYPE OF NUCLEAR DIVISION PROCESS Mitosis Meiosis (Zygotic, Gametic, Sporic)

  3. Evolutionary Advances (II) 8) TYPE OF LIFE CYCLEHaplobiontic Haploid   Diplobiontic Isomorphic Haplobiontic Diploid   Diplobiontic Heteromorphic   9) MODE OF REPRODUCTIONAsexual --------> Sexual [?? ----------> Asexual]  10) SEXUAL REPRODUCTION AS REGARDS GAMETE DIFFERENTIATIONIsogamy --------> Anisogamy --------> Oogamy  11) NUMBER OF OFFSPRINGMANY ----------> FEW  12) PROTECTION GIVEN REPRODUCTIVE PROCESS:NONE ----> MUCH

  4. Cell Complexity (I) Prokaryote to Eukaryote --- 1.5+ bya Serial Endosymbiosis Theory (SET) ??? Motility before nucleus ??? (? one origin ?) Nucleus --- endogenous origin in a thermoplasma type archean Mitochondrion --- from an aerobic bacterium (? one origin ?) Chloroplasts --- at least three separate origins

  5. Cell Complexity (II) Motility Structures Flagella in prokaryotes Flagella and cilia (? Undulipodia) in eukaryotes NOT the same thing as in prokaryotes Why use different names? Are undulipodia derived from spirochete bacteria? Did motility (undulipodia) come before the nucleus?

  6. SET (Lynn Margulis)

  7. Primary Endosymbiosis

  8. Secondary Endosymbiosis

  9. Organism Complexity Unicellular Colonial Multicellular Advantages? Specialization Organisms do not always get more complex (e.g. – yeast, some parasites)

  10. Organism Size Generally smaller to larger BUT sometimes larger to smaller Advantages of being smaller? Smaller habitats / fewer resources needed Shorter life cycle (more chance for genetic change) (? faster evolution ?)

  11. Organism Life Span Generally shorter to longer BUT sometimes longer to shorter Advantages of shorter life span? Reach reproductive maturity sooner Go through more generations in a shorter period of time Thus more chance for genetic change) (? faster evolution ?)

  12. Type of Nutrition SEE HANDOUT 3.5+ bya --- heterotrophic (anaerobic) ??? --- anaerobic chemoautotrophs 3.0+ bya --- Type I photoautotrophs 2.8+ bya --- Type II photoautotrophs ??? --- aerobic heterotrophs ??? --- aerobic chemoautotrophs

  13. Chemoautotrophism ANAEROBIC -- Methanogens -- Domain Archaea  XH + CO2 ---> XCOOH ---> XCHO ----*-----> XCH3 ------#---------> CH3 *Some energy release # methylcobalamin + HSO3(CH2)2SH (X is an unknown carrier molecule) AEROBIC -– Domain Bacteria Nitrosomonas spp. (Nitrifying Bacteria) NH4 + 2O2 -----> 2H2O + NO2- + energy Nitrobacter spp. (Nitrifying Bacteria) 2NO2- + O2 -----> 2NO3- + energy Ferrobacillus ferrooxidans (Iron Bacteria) 4FeCO3 + O2 + 6H2O -----> Fe(OH)3 + 4CO2 + energy Thiobacillus thioxidans (non-photosynthetic Sulfur Bacteria) 2S + 3O2 + 2H2O -----> 2H2SO4 + energy

  14. Photoautotrophism light CO2 + 2H2X -------> (CH2O) + H2O + 2X Type I Photosynthesis (non-oxygenic): light CO2 + 2H2S -------> (CH2O) + H2O + 2S Type II Photosynthesis (oxygenic): light CO2 + 2H2O -------> (CH2O) + H2O + O2

  15. Genome Content Haploid (n) to Diploid (2n) Terms refer to nuclear content Advantages of Diploidy?

  16. Type of Nuclear Process Mitosis (1.5+ bya) What does mitosis do? A ‘conservative’ division Meiosis (1.2+ bya) What does meiosis do? Sexually reproducing organisms MUST have meiosis somewhere in their life cycle! Meiosis & sexual reproduction make for VARIATION!

  17. Mode of Reproduction Asexual to sexual BUT, sexual to asexual in some cases Advantages / disadvantages of sex? Or Why is variation “good” and why is it “bad”? Advantages of haplodiploidy?

  18. Complexity of Life Cycle (I) Haplobiontic Haploid (has zygotic meiosis) Haplobiontic Diploid (has gametic meiosis) Diplobiontic (has sporic meiosis) -- isomorphic or heteromorphic -- in heteromorphic either the n or 2n phase can be the dominant one

  19. Haplobiontic Haploid Life Cycle

  20. Haplobiontic Diploid Life Cycle

  21. Diplobiontic Life Cycle

  22. Gamete Differentiation Isogamy Anisogamy Oogamy

  23. Number of Offspring /Protection Given to Reproduction Many Usually with little or no care; often with external fertilization Few Usually with considerable care; usually with internal fertilization

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