Figure 6 : Extrinsic and intrinsic noise.

From: Digital Signal Processing and Control for the Study of Gene Networks

Figure 6

(A) There is no noise affecting xprotein and yprotein levels. (B) Extrinsic or global noise obeying a normal distribution (mean: 0, standard deviation: 1) is added to xprotein only. Although no noise is added to yprotein, fluctuations in yprotein levels are observed, which is intrinsic noise caused by extrinsic noise propagated from xprotein to yprotein. (C) Extrinsic noise is added to yprotein.