5 - Communication of information from the genome to the proteome

Summary

The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point. Frequently the messages have meaning; that is they refer to or are correlated according to some system with certain physical or conceptual entities. These semantic aspects of communication are irrelevant to the engineering [biological] problem. The significant aspect is that the actual message is one selected from a set of possible messages. The system must be designed to operate for each possible selection, not just the one which will actually be chosen since this is unknown at the time of design.

Shannon (1948)

Genetics and the standard communication system

The components of the genetic communication system

Let us now consider the model shown in Figure 5.1 of a general communication system commonly used by communication engineers. The object of such systems is to accept messages from the source and to transmit them through a channel to the destination as free from errors as the specifications given to the design engineer require. The source generates an ensemble of messages written in the finite source alphabet, A. The message is encoded from the source alphabet to the channel alphabet for transmission through the channel. At all stages of the communication the message is acted on by a second chance or stochastic process (see Markov process in The Mathematical Appendix) that interchanges some letters in a random and nonreproducible fashion. The result of this process is called noise.