# so good.

Javier Garcia-Bernardo

Computer Science Master Student

Math 303. Complex Networks

## Background

Genetic networks

Single input motifs

## Downstream Gene Expression

Small fluctuations in Activator

## Coordination

$P_{Fixed}(n)&space;=(kAct)^n&space;\\&space;P_{Pulsing}(n)&space;=&space;\frac{T_{ON}}{T_{ON}+T_{OFF}}\left(kAct\frac{T_{ON}+T_{OFF}}{T_{ON}}\right)^n&space;+&space;\frac{T_{OFF}}{T_{ON}+T_{OFF}}(k0)^n&space;=&space;(kAct)^n\left(\frac{T_{ON}+T_{OFF}}{T_{ON}}\right)^{n-1}&space;\\$ \begin{align*}&space;&T_{ON}&space;=&space;120&space;\\&space;&T_{OFF}&space;=&space;120&space;\\&space;&Act&space;=&space;250&space;\\&space;\end{align*}&space;\\

## Noise in Gene Expression

Intrinsic: Affect to only one gene.

E.g. RNApolymerase binding to a promoter

Inherent to the Gillespie Algorithm

Extrinsic: Affect to all genes

E.g. Fluctuations in the levels of the RNApolymerase

Modelled with a Ornstein–Uhlenbeck process

## TATA box example

Lots of genes in stress response in yeast have a TATA box.

Is that advantage due to coordination?

Has noise evolved?

Wow

## Conclusions

Small fluctuations in the Activator

coordinate expression of Downstream genes.

Even Infrequent coordination helps to bet-hedge

against sudden changes in the environment.

They do this without cost (Not shown).

Noise can produce the fluctuations.

By Javier GB

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