DNA may not be life's instruction book -- just a jumbled list of ingredients 22 April 2020
A new framework recasts heredity as a complex, networked information system in which all the regulatory molecules that help the cell to function can constitute a store of hereditary information. Instructions not coded in the DNA are contained in the arrangement of the molecules within cells and their interactions with one another. This arrangement of molecules is preserved and passed down from one generation to the next. framework recasts inheritance as the combined effects of three components: entities, sensors and properties. Sensors are specific entities that interact with and respond to other entities or to their environment. Sensors respond to certain properties, such as the arrangement of a molecule, its concentration in the cell or its proximity to another molecule. Together, entities, sensors and properties enable a living organism to sense or 'know' things about itself and its environment. Some of this knowledge is used along with the genome in every generation to build an organism. Scientists don't currently have methods to measure some of these things, so this work points to potentially important new avenues for research. 3
The information in a cell code can be conceptually separated into two distinct forms. One is the genome sequence, where information is stored in a linear sequence of bases, and the other is the recurring arrangement, where information is stored in the concentrations, configurations and interactions of molecules in bottleneck stages (see electronic supplementary material on cell code assembly). While the information content in this arrangement and the extent to which it is recreated is currently not easily quantified, it is clear that heredity relies on information that is held in multiple stores and transmitted across generations.
Of particular relevance are self-replicating machines that use the same store of information in two distinct ways:
(i) as instructions whose interpretation leads to the construction of an identical copy of the machine and
(ii) as data to be copied without interpretation and placed in the copied machine.