Table 1.

The four classes of first-order reactions considered in the stochastic model

Label	Type of reaction	Reaction	Rate
I	Production from a source	$\varphi \to {\mathcal{M}}_i$	$k_i^S$
II	Degradation	${\mathcal{M}}_i\to \varphi$	$k_i^d{n}_i$
III	Conversion	${\mathcal{M}}_j\to {\mathcal{M}}_i$	$k_{ij}^{con}{n}_j$
IV	Catalytic production from source	$\varphi \stackrel{{\mathcal{M}}_j}{\to }{\mathcal{M}}_i$	$k_{ij}^{cat}{n}_j$