Effect of cell-to-cell variation on power spectrum of the motor in the full pathway model. (A) Predictions about how different cell parameters affect the motor power spectrum, in particular its low-frequency component. The black line (wild-type WT1) is the same as the total motor spectrum in Fig. 4, right. The motor spectra for increased motor switching rates (MS; red line), as well as reduced rates of receptor methylation and demethylation (M; green line) and the total number of receptors (blue line) are shown as well. Arrows indicate the features in the spectra that are affected. Dashed box is the area shown in panel (B). (B) Motor spectrum of cells with low motor bias (black line), as well as the component from steady-state motor switching only (grey line). (Inset) Measured power spectra for wild-type cells (WT2) with low motor bias (black) and mutant lacking the signalling pathway (grey). Axes are the same as in the main panel. Error bars indicate the measurement uncertainty. Spectra were traced from data presented by Korobkova et al. . Model parameters are listed in the Methods. (C) Motor spectrum of cells with varying CheR expression level. Shown are WT2 (black line; same as in panel B), as well as 2- (red), 4-(green) and 10-fold (blue) CheR-expression level compared to wild-type. (Inset) Measured power spectra of cells with corresponding CheR-expression level (see main panel). Axes are the same as in the main panel. Spectra were traced from data presented by Korobkova et al. . Model parameters are listed in the Methods.