M N ] 2 8 M ay 2 01 3 Stochastic gene expression with delay by

The expression of genes usually follows a two-step procedure. First, a gene (encoded in the genome) is transcribed resulting in a strand of (messenger) RNA. Afterwards, the RNA is translated into protein. We extend the classical stochastic jump model by adding delays (with arbitrary distributions) to transcription and translation. Already in the classical model, production of RNA and protein comes in bursts by activation and deactivation of the gene, resulting in a large variance of the number of RNA and proteins in equilibrium. We derive precise formulas for this second-order structure with the model including delay in equilibrium.