  Living systems transmit heritable information using the replicating gene
sequences and the cycling regulators assembled around gene sequences. Here I
develop a framework for heredity and development that includes the cycling
regulators parsed in terms of what an organism can sense about itself and its
environment by defining entities, their sensors, and the sensed properties.
Entities include small molecules (ATP, ions, metabolites, etc.), macromolecules
(individual proteins, RNAs, polysaccharides, etc.), and assemblies of
molecules. While concentration may be the only relevant property measured by
sensors for small molecules, multiple properties that include concentration,
sequence, conformation, and modification may all be measured for macromolecules
and assemblies. Each configuration of these entities and sensors that is
recreated in successive generations in a given environment thus specifies a
potentially vast amount of information driving complex development in each
generation. This Entity-Sensor-Property framework explains how sensors limit
the number of distinguishable states, how distinct molecular configurations can
be functionally equivalent, and how regulation of sensors prevents detection of
some perturbations. Overall, this framework is a useful guide for understanding
how life evolves and how the storage of information has itself evolved with
complexity since before the origin of life.
