Figure 1. Schematic representation of the quality state-space and processes in the reference simulation.

(A) The quality state-space consists of a finite number of discrete states referring to the functional quality of mitochondria with distribution . (B) Mitochondria with functional quality and undergo fusion–fission events into quality levels and under functional quality conservation: . (C) Mitochondria are subjected to molecular quality decay resulting in an overal downward-shift of . (D) Mitophagy gives rise to a loss of mitochondria in quality state , while biogenesis of mitochondrial mass results in a gain of mitochondria in quality state . Imposing homeostatic conditions, the norm of remains constant at all times.