life takes place only in environments with an excess of energy: in our case, in the sunlight. This concept includes the following facts:
- Cells have to feed continuously
- Cells have to breath continuously
- Cells cannot ever stop producing energy
- Cells use energy to keep many ionic gradients (Ca++, Na+, K+, Cl- etc.)
Gradients are necessary for most cell functions (signal transduction, glucose and AA transport, etc.)
formation of evolutionary trees for any molecule and organism mediated by irreversible bifurcation followed by selection. The driving forces of bifurcation and selection depend on the environment and can be considered "local".
at any level from the molecules to the species, precise feedback mechanisms can be identified that regulate the number of the objects involved in the equilibrium.
in any self-regulatory cyclic system the number of any item is changing in time with a periodicity that depends on the size of the system - from seconds for chemical reactions to years for prey/predator relationships - and the time the feedback signals need to diffuse across the system.
as biological systems tend to expand exponentially in a finite environment, they become - sooner or later - limited in their growth due to a shortage in some essential factor ("nutrient"). The competition for the limiting nutrient will locally drive the selection.
Concept of "essential" nutrient (Metal ions (Zn, Cu, Fe, Se), Inorganic phosphate
Selected aminoacids, Vitamins (why eating vitamins is better than producing them by themselves)
A deep knowledge of the basic features of living organism will allow modelling of robust networks (Computational systems biology 2002)
Systems Biology: A Brief Overview Hiroaki Kitano 2002
Danielle S. Bassett. Modeling networks