Marcelo Gleiser, Sara Imari Walker
A key open question in the study of life is the origin of biomolecular
homochirality: almost every life-form on Earth has exclusively levorotary amino
acids and dextrorotary sugars. Will the same handedness be preferred if life is
found elsewhere? We review some of the pertinent literature and discuss recent
results suggesting that life's homochirality resulted from sequential chiral
symmetry breaking triggered by environmental events. In one scenario,
autocatalytic prebiotic reactions undergo stochastic fluctuations due to
environmental disturbances. In another, chiral-selective polymerization
reaction rates influenced by environmental effects lead to substantial chiral
excess even in the absence of autocatalysis. Applying these arguments to other
potentially life-bearing platforms has implications to the search for
extraterrestrial life: we predict that a statistically representative sampling
of extraterrestrial stereochemistry will be racemic (chirally neutral) on
average.
View original:
http://arxiv.org/abs/1202.5048
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