  Important aspects of the process of information storage and retrieval in DNA
and RNA, and its evolution, are the role of the anticodons and associated
$t$RNA's, and correlations between anticodons and amino acids; the degeneracy
of the genetic code, and the periodicity of many amino acid physico-chemical
properties. Such factors are analysed in the context of a $sl(6/1)$
supersymmetric model of the genetic code.
