dimanche 18 janvier 2009

「生命を定義する」 Définir la vie (7)

5 février 2008

Antonio Lazcano "The origin and nature of first life" his article

Schrödinger "What is life?" (1994)
Avery, Oswald T., Colin M. MacLeod, and Maclyn McCarty. Studies on the chemical nature of the substance inducing transformation of pneumococcal types. Journal of Experimental Medicine 79: 137-158, 1944.

At the time, no books on the life.

What is life (how did it originate) ?
1) autopoiesis
2) self-organization & complex system (popular among physicists, not biologists)
3) emergence of genetic informations & Darwinian evolution

● cyanobacteria: autpoietic system but not enough for life
● complex organization is not unique to living systems
   cellular automata
   flowing fluids
   falling droplets
   Belousov-Zhabotinsky reaction (BZ reaction) (video)

   "No single rule for all these"

● self-organization of prebiotic components must have been important
● genetic information & physical/chemical laws are necessary
● history's contingency is involved
● physical system is complex, but lacks genetic systems, historical continuity, ie, genealogy
● some systems may have genealogy but not genetic (eg, roman kings)

origin of life
  prebiotic evolution -----> ? <------ a="" about="" are="" biological="" evolution="" href="http://en.wikipedia.org/wiki/Oparin" knows="" nobody="" only="" process="" target="_blank" theories="" there="" this="">Oparin's theory is most reliable

  Stanley Miller experiment (1953) 不当に批判された
    CO2, CO, N2, H2S, H2O, CH4 ---> aa, nucleobases, sugars, lipids, oligomers of biochemical compounds

autocatalytic systems ---> non-informational character, not genetic system, cannot evolve by natural selection because they do not store information in a stable manner --- "they don't have genetic history"

For life, genetic replicating mechanism is required.

  non-living ---------------> living
      "meaningless to draw a line"

   (his analogy: if you look at Mark Rothko's carefully, there is no clear boundary between lines)


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