Origin of Life

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Origin of Life
2012-01-25 21:28:20

biology 1215
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  1. What is necessary for the formation of organic molecules? and why?
    could have formed by from simple molecules

    first organic compouinds formed near submerged volcanoes; Ammonia, carbon dioxide, methane, water vapor, and hydrgen gas ( released by volcanic activity )

    - gases have 4 key elements of an organic molecule (C,H,O,N) present and the absence of free oxygen in the atmosphere allowed the formation of organic molecules.
  2. how did the absence of free oxygen in the atmosphere allow for the formation of organic molecules?
    breaks what holds the atoms together(chemical bonds); oxygen destroys the chemical bonds
  3. why was there lightning from frequent, intense electrical storms and UV radiation from the sun?
    no o-zone layer, which protects from uv light
  4. how did Miller-Urey simulate the primitive conditions of earth in a laboratory setting?
    -In the aparatus- showed the primitive atmosphere, put in gases (CH4, CO2,NH3,H2) to stimilate atmosphere

    -used electrodes that discharge sparks as source of energy ( lightning simulation)

    -used heated water to simulate ocean
  5. simple organic building blocks polymerized to form more complex and stable organic molecules how?
    when ocean spashed magma, caused it to evaporate and molecules become more condensed
  6. What are protobionts?

    all concentrated water molecules that repel back fat molecules, non living, predecessors of living cells, form spontaneously

    - collections of abiotically produced molecules surrounded by a membrane-like structure
  7. how do protobiont form spontaneously?
    - from abiotically produced organic compunds

    example: certain small membrane bounded droplets called liposomes can form when lipids or other organic molecules are added to water, the hydrophobic molecules in the mixture organize the bilayer at the surface.

    lipsosomes can reproduce and perform simple metabolic reactions.
  8. how do protobionts show signs of life?
    • 1. fat can grow in size, by water and molecules to enter (GROWTH)
    • 2. once it gets to certain size it splits and 2 strands of DNA form
    • 3. makes 2 protobiont, almost like cell division
    • 4. responds to stimuli and inside negative and outside positive ( if you touch droplet, charge difference reverses )
    • 5. excitability
  9. RNA was the first important molecule in protobionts why?
    • 1. its genetic material has information like DNA
    • 2. replicates itself; if leave free sloating can carry out complementary base pairing
    • 3. speed up chemical reaction (same as enzyme reaction)
  10. DNA replaced RNA as the primary genetic material, why?
    • RNA is just a single stranded strand, DNA is double stranded helix, which means stronger and more stable
    • -DNA replicated more accurately

    For example, can cut out section of DNA and still repair b/c of double stranded
  11. Prokaryotes were the first cells on earth, why?

    b/c they are so simple, have proof from fossils, no nucleus, no membrane bound organelles, no ER, no golgi
  12. what is the autogenous model? explain.
    how organelles form by the infolding of the cells own plasma membrane

    Ex. ER, golgi, nuclear membrane
  13. what is serial endosymbiotic model? explain.

    more complex; engulfing of photosynthetic bacteria -> cyanbacteria, tep formation and bringing bacteria and co exist with the other bacteria

    -The proposal that plastids, mitochondria, and possibly also cilia and flagella arose from symbiotic prokaryotic organisms living within a eukaryotic host cell.
  14. explain how chlorplasts and mitochondia resemble prokaryotes?
    prokaryotes: circular DNA and ribosomes, splits and makes copies of DNA by binary fission

    BOTH: same size

    Mitochondra: circular DNA and ribosomes, can divide on its own, inner membrane will be similar of bacteria