  All known life forms are based upon a hierarchy of interwoven feedback loops,
operating over a cascade of space, time and energy scales. Among the most basic
loops are those connecting DNA and proteins. For example, in genetic networks,
DNA genes are expressed as proteins, which may bind near the same genes and
thereby control their own expression. In this molecular type of self-reference,
information is mapped from the DNA sequence to the protein and back to DNA.
There is a variety of dynamic DNA-protein self-reference loops, and the purpose
of this remark is to discuss certain geometrical and physical aspects related
to the back and forth mapping between DNA and proteins. The discussion raises
basic questions regarding the nature of DNA and proteins as self-referring
matter, which are examined in a simple toy model.
