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signal frequency, and signal duration because the phosphatase must shut down fast enough.

Kinases are important for the regulation of signal amplitude and signal height, because the

kinase must amplify strongly enough.

Finally, however, the recognition and decoding of such signals with the aid of bioinfor­

matics is also medically important. An important example, for example, was the third

phosphorylation in Erk kinase, which supports heart failure (see Chap. 5). Many cancers

arise from the fact that a mutation in a body cell causes a growth kinase to be constantly

turned on. An important example is the B-Raf kinase. Unmutated, it allows skin cells to

grow. In the mutated version, such as from too much UV radiation while tanning at the

beach, it leads to melanoma, or black skin cancer. How good it is that sunburns cause the

skin to exfoliate: These skin cells have all voluntarily perished (via the cell death or apop­

tosis pathway) so they don’t harm us as cancer cells. This apoptosis pathway is another

equivalent of check bits in a computer: in particular, the p53 protein makes sure that either

DNA repair still works successfully and is carried out, or the cell goes into apoptosis. The

miRNAs are also important regulators in cancer (Lujambio and Lowe 2012). Constant

coding and decoding is vital to us, and it is exciting to trace this using bioinformatics

(Richard et al. 2016).

Conclusion

• Shannon has made it possible to measure how much information is contained in

a message. It is calculated how many bits of information are contained in each

word of the message. For example, a nucleotide in DNA comes in four forms. To

identify one, I have to answer two yes/no questions (is it a purine/pyrimidine?

Which of the two purines/pyrimidines is it?), so a nucleotide carries two bits .

• Interestingly, one can thus identify any number of codes, languages and codings

in the cell. Since living cells are not computers, but numerous biochemical reac­

tions run simultaneously side by side and sometimes quite disorderly, thus caus­

ing a lot of commotion and disturbances, it is important to send this information

as clearly as possible, for example to amplify signals through signal cascades.

The more precisely the signal is understood and implemented in the cell, the bet­

ter the cell survives. Therefore, survival pressure already ensured that the genetic

information is well encoded and well transferred into various other codes.

• Bioinformatics only has to replicate this in the computer programs used and can

then decipher and “crack” code after code in the cell quite accurately. A good

starting point for using this are the numerous programs for sequence analysis,

which are explained here from the first chapter onwards. Sequence analyses have

therefore also become the most important basic tool in bioinformatics.

7.3  Understanding Coding Better