Friday, 3 January 2014

Why is genetic information stored in digital form?

The answer is short yet profound [1]. 

Genetic information of living organisms is stored on biopolymers in digital form as it is the only way to transmit information through a physical noisy channel with as little error as possible. According to Shannon's noisy channel coding theorem, it is possible to transmit information via a physical noisy channel virtually without losses provided the information transmission rate is less than the channel's capacity. In other words, provided the above condition holds, for any noise level there exists a code which guarantees virtually error-free transmission. Analog systems do not ensure this because they do not employ codes. 

Information transmission is central to protein life. The only way genetic information can be transmitted to progeny with minimal losses is by using a digital information system. This is the case for all protein life as it employs a digital base-four nucleotide code: 

  • {A=adenine, C=cytosine, G=guanine, T=thymine} in DNA 
  • {A=adenine, C=cytosine, G=guanine, U=uracil} in RNA. 

So reliable information transmission is impossible without a code, which, in turn, infers agency (details here). 

  1. H.P. Yockey, Information Theory, Evolution and the Origin of Life.

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