  Molecular chirality is inherent to biology and cellular chemistry. In this
report, the origin of enantiomeric selectivity is analyzed from the viewpoint
of the "RNA World" model, based on the autocatalytic self-replication of
glyceraldehyde as a precursor for simple sugars, and in particular ribose, as
promoted by the formose reaction. Autocatalytic coupling of formaldehyde and
glycolaldehyde produces glyceraldehyde, which contains a chiral carbon center
that is carried through in formation of the ribose ring. The parity
non-conserving weak interaction is the only inherently handed property in
nature and is herein shown to be sufficient to differentiate between two
enantiomeric forms in an autocatalytic reaction performed over geologically
relevant time scales, but only in the presence of a catalytic metal ion such as
divalent calcium or higher Z alkaline earth elements. This work details
calculations of the magnitude of the effect, the impact of various
geologically-available metal ions, and the influence on evolution and dominance
of chirality in the molecules of life.
