Information Technology Reference
In-Depth Information
(see Fig. 3.10). The
source
of a cascade is the reactant of the first reaction, while
its
destination
is the product of the last reaction of its sequential composition. A
cascade can be either perfectly linear, or sharing substances (reactants or products)
with other reactions.
Fig. 3.10
Sequencing
Fig. 3.11
Cycling
A (transformation) cycle is a sequential composition where the destination coin-
cides with the source of the cascade.
Coupling reactions means that their fluxes are correlated. This does not mean
that the two reactions can be considered as a single reaction. In fact, in general their
fluxes can be different, but for example, the flux of one reaction could be the square
of the flux of another one.
Fig. 3.12
A kind of homeostasis
Homeostasis can occur in many forms. The example given in Fig. 3.12 shows a
simple case of homeostasis where the amount of a given substance is automatically
kept to a fixed value
K
(if a quantity
f
is consumed, then the difference with
respect to the fixed value
K
is introduced from outside).
(
X
)
