Fig 1. Self-replicator model of bacterial growth.
External substrates S enter the cell and are transformed into precursors P through the action of the metabolic machinery M. The precursors are used by the gene expression machinery R to make the proteins composing both the metabolic machinery (transporters, enzymes,…) and the gene expression machinery itself (RNA polymerase, ribosomes,…). α (1 − α) is the mass proportion of precursors converted into R (M). Thick arrows denote reactions and thin, dashed arrows denote catalytic activities. The rate of synthesis of precursors and the rate of synthesis of proteins from precursors are denoted by VM and VR, respectively.