Rules of the Cell Cycle Automaton

The automaton model for the cell cycle (Fig. 10.1a) is based on the following assumptions  

The cell cycle consists of four successive phases along which the cell progresses Gl, S (DNA replication), G2, and M (mitosis). 

Upon completion of the M phase, the cell transforms into two cells, which immediately enter a new cycle in Gl (the possibility of temporary arrest in a GO phase is considered elsewhere). 

Each phase is characterized by a mean duration D and a variability V. As soon as the prescribed duration of a given phase is reached, the transition to the next phase of the cell cycle occurs. The time at which the transition takes place varies in a random manner according to a distribution of durations of cell cycle phases. In the case of a uniform probability distribution, the duration varies in the interval [D(l - V), D( 1 + V)]. 

We use these rules to simulate the dynamic behavior of the cell cycle automaton in a variety of conditions. Table 10.1 lists the values assigned in the various figures to the cell cycle length, presence or absence of cell cycle entrainment by the circadian clock, initial conditions, variability of cell phase duration, and probability of quitting the cell cycle. 

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