Ask A Scientist© Molecular Biology Archive

name         Lance
status       other
age          15

Question -   I realize that there are some problems with the
possibility of silicon-based life. Carbon can form stable bonds with many
elements and that makes it a good material to construct life upon. Would
there be any similar problems with a nitrogen-based lifeform?


The following might be helpful:
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980221b.html

  Anthony Brach
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Well, to an extent, WE are nitrogen-based life forms.  Nitrogen atoms are
part of the backbones of proteins, which are fundamental constituents of all
living things.  Nitrogen isn't part of the backbone of DNA and RNA, but it
does play a part in the structure of those molecules.  (Carbon, oxygen, and
phosphorus are in DNA and RNA backbones - should we say that we are
phosphorus and oxygen-based life forms, too?)

CArbon is a more convenient designation for a base because it forms stable
chains with an all-carbon backbone.  No other element does anything like
this.  Silicon comes close, making very stable polymeric chains with
alternating silicon and oxygen atoms.  All-nitrogen chains are very
unstable.  As I said before, though, nitrogen is part of the very important
linkages in proteins.  This gives the chemistry of life a richness and
versatility that it could not have with carbon and hydrogen alone.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois
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