Two operative concepts for the post-genomic era: the "mémoire vive" of the cell and a molecular algebra.

The first successes in cloning experiments and stem cell "reprogramming" have already demonstrated the primordial role of cellular working-space memory and regulatory mechanisms, which use the knowledge stored in the DNA database in read mode. We present an analogy between living systems and informatics systems by considering: 1) the cell cytoplasm as a memory device accessible as read/write; 2) the mechanisms of regulation as a programming language defined by a grammar, a molecular algebra; 3) biological processes as volatile programs which are executed without being written; 4) DNA as a database in read only mode. We also present applications to two biological algorithms: the immune response and glycogen metabolism.