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Bio. 230 --- Evolution II
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Evolutionary Advances (I) 1) CELL COMPLEXITY Prokaryote ----------> Eukaryote 2) ORGANISM COMPLEXITY Unicellular ---> Colonial ---> Multicellular 3) ORGANISM SIZE Smaller -------> Larger [?? ---------> Less Large] 4) ORGANISM LIFESPAN Short --------> Longer [?? ----------> Shorter] 5) TYPE OF NUTRITION Heterotrophic ----------> Autotrophic 6) GENOME CONTENT Haploid -------> Diploid 7) TYPE OF NUCLEAR DIVISION PROCESS Mitosis Meiosis (Zygotic, Gametic, Sporic)
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Evolutionary Advances ( II ) 8) TYPE OF LIFE CYCLE Haplobiontic Haploid Diplobiontic Isomorphic Haplobiontic Diploid Diplobiontic Heteromorphic 9) MODE OF REPRODUCTION Asexual --------> Sexual [?? ----------> Asexual] 10) SEXUAL REPRODUCTION AS REGARDS GAMETE DIFFERENTIATION Isogamy --------> Anisogamy --------> Oogamy 11) NUMBER OF OFFSPRING MANY ----------> FEW 12) PROTECTION GIVEN REPRODUCTIVE PROCESS: NONE ----> MUCH
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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
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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?
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SET (Lynn Margulis)
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Primary Endosymbiosis
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Secondary Endosymbiosis
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Organism Complexity Unicellular Colonial Multicellular Advantages? Specialization Organisms do not always get more complex (e.g. – yeast, some parasites)
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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 ?)
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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 ?)
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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
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Chemoautotrophism ANAEROBIC -- Methanogens -- Domain Archaea XH + CO 2 ---> XCOOH ---> XCHO ----*-----> XCH 3 ------#---------> CH 3 *Some energy release # methylcobalamin + HSO 3 (CH 2 ) 2 SH (X is an unknown carrier molecule) AEROBIC -– Domain Bacteria Nitrosomonas spp. (Nitrifying Bacteria) NH 4 + 2O 2 -----> 2H 2 O + NO 2 - + energy Nitrobacter spp. (Nitrifying Bacteria) 2NO 2 - + O 2 -----> 2NO 3 - + energy Ferrobacillus ferrooxidans (Iron Bacteria) 4FeCO 3 + O 2 + 6H 2 O -----> Fe(OH) 3 + 4CO 2 + energy Thiobacillus thioxidans (non-photosynthetic Sulfur Bacteria) 2S + 3O 2 + 2H 2 O -----> 2H 2 SO 4 + energy
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Photoautotrophism light CO 2 + 2H 2 X -------> (CH 2 O) + H 2 O + 2X Type I Photosynthesis (non-oxygenic): light CO 2 + 2H 2 S -------> (CH 2 O) + H 2 O + 2S Type II Photosynthesis (oxygenic): light CO 2 + 2H 2 O -------> (CH 2 O) + H 2 O + O 2
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Genome Content Haploid (n) to Diploid (2n) Terms refer to nuclear content Advantages of Diploidy?
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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!
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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?
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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
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Haplobiontic Haploid Life Cycle
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Haplobiontic Diploid Life Cycle
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Diplobiontic Life Cycle
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Gamete Differentiation Isogamy Anisogamy Oogamy
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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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