Within a heteroplasmic cell containing different types of mtDNA molecule (left), different processes (right) can change the structure of the cellular mtDNA population. These include replication, degradation, de novo mutation, intercellular transfer, and recombination. Cell divisions, where mtDNA molecules may be partitioned between daughter cells according to several possible mechanisms, also influence mtDNA statistics. The rates of these processes depend on organism-, sequence-, tissue-, and time-dependent factors. Several correspond directly to processes from the theory of stochastic population processes [57,58].