“Superimposed on the hierarchical framework of defined components of a cell there is another layer. This second layer is highly flexible and can take on an almost infinite variety of forms, like soft and responsive flesh on a bony skeleton. The deep question is whether this higher layer in the construction of cells is itself organized. Are there hierarchies, or at least rules, in the protein-modifying, RNA splicing, gene-regulating processes of a cell? If so, then we have a chance of understanding them. If not, we will never know exactly what a cell will do next. If the detailed chemistry of the cell is simply the outcome of a historical ragbag of ad hoc interactions, then it will be no more predictable than the weather. I do not have an answer to this question. But two features of cells might be relevant. One is a sense of time, or causation - knowledge of the way that things in the real world follow in a certain sequence. The other is integrity, which enables a cell to distinguish between what belongs to itself and what belongs to the outside world.” Systems Biology Book:Wetware: A Computer in Every Living Cell Source: Wetware: A Computer in Every Living Cell