Biology Reference
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(a)
A
P
+
(b)
A
B
AB
+
(c)
AB
A
B
+
+
(d)
AX
B
A
BX
Figure 2
Basic fabrication processes.
(a) The atoms of A are rearranged into a new configuration P. A and P have the same atomic
composition and are either structural or conformational isomers of each other; (b) Synthesis of a
new molecule AB from A and B, or an association of A and B to form a non-covalently bound
complex AB; (c) Degradation of AB to two fragments A and B, or the dissociation of a complex
AB into components A and B; (d) The synthesis of two molecules A and BX through the transfer
of a part of a donor molecule AX to acceptor molecule B.
representations. For example, I could have written the process A
+
B
→
AB as
A
+
B
→
C, but that obscures the fact that C must contain exactly the atoms of
A and B.
In general, therefore, I consider both the input and output to a fabrication
process to be a material object, which can be considered a unit with a fixed
internal arrangement of components ('atoms'). The fabrication process itself
involves either an internal rearrangement within an input object, the combining
of objects, the splitting of an object, or the transfer of part of one object to
another. Following Rosen (1991), the fabrication process can in the abstract be
regarded as a mapping f from a domain (a set A of input objects) to a codomain
(a set B of output objects). Such a mapping is usually depicted as
f
→
B
fA
→
B or, equivalentlyA
(1)
Any specific conversion of a
∈
A to b
∈
B can be depicted with the 'mapsto'
notation
a
→
fa or, equivalentlya
→
b
(2)
This mapping is the fundamental relationship on which Rosen (1991) builds his
relational theory of biology.
Whereas, the nature of A and B is reasonably clear, that of f is not. Is it just a
process or is it itself a physical object? We shall see below that f can be either.
