Biology 2

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Biology 2
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2011-02-28 23:19:17
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biology
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  1. Parsimony
    (selection of trees)
    The tree that is the simplest explanation of relationships is the tree adopted.
  2. Maximum Likelihood
    (selection of trees)
    Molecules
  3. Monopyletic
    A group that includes the ancestrial species and ALL of its descendents
  4. Paraphyletic
    A group that consists of an ancestrial species, and some, but not all of the descendents
  5. Polyphyletic
    A grouping of several species that lack a common ancester.
  6. Early Earth
    4.6 billion years ago

    Molten Planet
  7. First Rocks
    3.8 billion years ago

    • 1. Abiotic synthesis of organic molecules
    • 2. Synthesis of polymers
    • 3. Protobionts
    • 4. First Genetic Material
  8. Abiotic (non-living) Synthesis of Organic Molecules = Abiogenesis
    -1920's Oparin-Haldane Hypothesis

    -1953 Stanley Miller & Harold Urey
  9. Oparin-Haldane Hypothesis
    • Reducing atmosphere + lightening/UV light =
    • organic molecules
  10. Stanley Miller & Harold Urey
    • -created early earth's atmosphere (CH4 NH4 H2O H2S)
    • -when they added lightening--->produced small organic molecules
    • -this hypothesis was controversial since some support the idea that early earth was not very reducing & made up mainly of CO2 & N2 gas
  11. Synthesis of Polymers
    -replication by dripping solutions of amino acids on hot sand, clay or rock
  12. Protobionts
    Abiotic groups of molecules surrounded by a membrane

    • ex: Liposomes = lipids + H2O
    • -"replicate"
  13. First Genetic Material
    -Probably RNA, not DNA
  14. Fossil Record - Provides the history of life
    1. Relative Dating

    2. Absolute Dating
  15. Relative Dating
    Certain rock layers above/below others w/ certain fossils give us a sequence of events
  16. Absolute Dating
    Determination of how old something is in calendar years

    • -based on decay of radioactive isotopes
    • -each radioactive isotope has half-life

    ex: C-14 half life: 5,730 years
  17. First Fossils
    • Stromatolites = Bacterial Mats 3.5 bya
    • -cyanobacteria
  18. 2.7-2.2 Billion years Ago
    • O2 levels begin to creep up
    • -banded-iron formations
  19. 2.1 Billion years ago
    • First Eukaryotes
    • -endosymbiont origin of mitochondria & plastids
    • -mitochondria = aerobic heterotrophic prokaryote
    • -plastid = photosynthetic prokaryote
    • -serial endosymbiosis
  20. Serial Endosymbiosis
    • 1. Mitochondria endosymbiosis likely occured first
    • -Found in all plants and animals

    • 2. Plastids - only found in plants
    • -Likely occured after mitochondrial endosymbiotic
    • event
  21. Evidence for Endosymbiosis
    1. Mitochondria & plastids have their own DNA

    • 2. Membranes of both are similar to those seen in
    • prokaryotes
  22. 1.5 Billion years ago
    • First Multicellularity
    • -small in size, limited in distribution
    • -likely evolved independently several times
    • -not much advancement after this point for a long time
  23. 570-550 Million years ago
    Larger, soft bodied organisms
  24. Cambrian Explosion
    • ~542 million years ago
    • -first hard-shelled organisms
    • -in first 20 million years most of the major animal phyla we know of originated (exceptions: Porifera-sponges & Chidaria-jellyfish)
    • Reasons for this:
    • 1. O2 levels
    • 2. Predator-prey relationships
  25. Archaean (Eon)
    4.6 bya - 2.5 bya
  26. Proterozoic (Eons)
    2.5 bya - 542 mya
  27. Phanerozoic (Eons)
    542 mya - Present
  28. Paleozoic Era
    542 mya - 251 mya (age of invertebrates)
  29. Mesozoic Era
    251 mya - 65 mya (age of reptiles)
  30. Cenozoic Era
    65 mya - Present (age of mamals)
  31. Major Events that Shaped Diversity During Phanerozoic
    • 1. Plate techtonics
    • 2. Mass Extinctions & Explosive Diversifications
  32. Plate Techtonics
    • -continents moving around via plate techtonics
    • -come together, break apart, come together, etc.
    • -create mountains, oceans, volcanoes, earthquakes

    ex: Pangea
  33. Pangea (250 mya)
    • -a single, large super continent
    • -reduced coastline
    • -higher gene flow possible
    • -more of the continental land mass is drier (more inland area)
    • -ocean currents change
  34. Mass Extinctions & Explosive Diversifications

    End Permian Extinction
    • -(251 mya)
    • *largest extinction in Earths history
    • *90% of all species go extinct
  35. Mass Extinctions & Explosive Diversifications

    End Cretaceous K-T Extinction
    • -65 mya
    • *asteroid impact in the Yucatan Peninsula (Alvarez,
    • 1980)
    • *wiping out dinosaurs (except birds)
  36. Prokaryotes

    2 Domains: Bacteria & Archaea

    Features:
    • 1. Smaller than Eukaryotes (1-5um)
    • 2. Generally single celled
    • 3. 3 common shapes (cocci, bacillus, spiral)
    • 4. Cell wall present
    • a) Bacteria-primarily PG
    • b) Archaea-mainly polysaccharides & protein, no
    • PG
    • 5. Many cell walls covered by a capsule (sticky outer layer that helps organism adhere to substrates
    • 6. About half can move in a direction (flagella)
    • 7. Generally lack internal membrane bound structures
    • 8. No nucleus
    • 9. Reproduce via binary fission
    • 10. Many have plasmids (smaller rings of DNA)
  37. Autotrophs
    Obtain food w/o eating other organisms

    • A) Photoautotrophs-light, CO2
    • B) Chemoautotrophs-inorganic chemicals, CO2
  38. Heterotrophs
    Obtain food by eating other organisms

    • A) Photoheterotrophs-light, organic compounds
    • B) Chemoautotrophs-organic compounds
  39. Oxygen Metabolism

    Obligate Aerobes
    Use and need O2 for cellular respiration
  40. Oxygen Metabolism

    Facultative Aerobes
    Use O2 if present, but can also use fermentation
  41. Oxygen Metabolism

    Obligate Anaerobes
    Poisoned by O2, only fermentation or other chemical energy used
  42. Nitrogen Metabolism
    Various types of Nitrogen used
  43. Bacteria-Proteobacteria
    • Gram Neg.
    • ex: E. Coli, Salmonella
  44. Bacteria-Chlamydias
    Gram neg., No PG
  45. Bacteria-Spirochetes
    • Helical
    • ex: syphilis, lime disease
  46. Bacteria-Gram +
    Ex: leprasy, lime disease
  47. Bacteria-Cyanobacteria
    Photoautotrophs
  48. Archaea
    Live in extreme environments

    • Thermophiles-hot environments
    • Halophiles-Salty environments
    • Methanogens-use CO2 and generate methane
  49. Archaea-Synampomorphies shared w/ Eukarya
    • 1. Lack PG in cell walls
    • 2. Several kinds of RNA Polymerase
    • 3. Introns present in DNA
    • 4. Histones present (proteins associated w/ chromatin)
    • 5. Use Methionine as initiator amino acid for protein synthesis
    • 6. Growth not inhibited by antibiotics

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