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Fig. 1.10
The graph of the structural formula of Adenine nucleotide. The atoms of Carbon
in positions 1
,
2
,
3
,
4
are not indicated.
1.8.2
Graphs of Reactions
Molecule structures are represented by graphs, but even chemical reactions acting
cooperatively and competitively over some substances are helpfully represented by
reaction graphs. A chemical reaction is naturally represented by means of a
multi-
edge
, which extends the notion of edge, because it has a set of source nodes and a set
of target nodes (it can be represented by a
body
with possibly many tails and many ar-
rows, as it is illustrated by Fig. 1.14). Namely, in a chemical reaction many reactants
are connected to many products.
Multigraphs
, which are based on
Multi-edges
, can
be also seen as graphs with two kinds of nodes (circles representing substances and
full circles representing reactions), and with two types of edges (tail edges and head
edges). Figure 1.14 describes chemical reactions expressed by a multigraph.
Fig. 1.11
The Nitrogenous bases
