Viroids -- the Nucleotide Game

Viroids are bare single-strand RNA loops of around 300 nucleotides causing plant diseases. They do not code for protein. The simplest of infectious agents, viroids would seem to be good candidates for thinking about the first genetic material.

These rules for the nucleotide game should result in viroids:

  1. Environments are composed of molecules occupying locations in a metric space with continuous or discreet time.

  2. There are an infinite variety of molecules possible.

  3. Reactions are transformations of molecules in close proximity to other molecules in close proximity, some of the resulting molecules being of types different from the reactants.

  4. There are an infinite number of possible reactions having positive probabilistic rates of reaction.

  5. Nucleotide elements of polymers spontaneously change at a low rate compared with the rate of nucleotide replication or complementation. These changes are called mutations.

  6. There exist nucleotide molecules which will replicate or complement a nucleotide polymer (template) under conditions which occur periodically.

  7. There are periodic conditions under which the replicated or complemented polymer will separate from its template.

  8. A nucleotide polymer species is called enduring if the probability of it or a replica surviving a replication cycle (polymerizing and separating period) is greater than one half. An unbounded number of distinct nucleotide polymer species are enduring.

  9. There are periodic conditions under which these nucleotide molecules will spontaneously bond together, forming or lengthening polymers.

  10. Some combinations or permutations of nucleotide molecules interact with other molecules differently than do other combinations of nucleotide molecules.

These conditions imply that there is some source of the nucleotide molecules (either new or recycled); and that those molecules are periodically available.

The periods may be continuous and simultaneous. Condition 9 bootstraps the process so there will be polymers to replicate.

Condition 10 guarantees that the genetic information matters; the arrangement of nucleotides in a polymer effects how it interacts with other molecules.

Because more than half of them survive, enduring molecules which replicate themselves will grow to outnumber the polymer species which don't endure. Certain species of nucleotide polymers will replicate more easily or have higher survival rates; such attributes will cause their numbers to increase relative to the others.

Notice that the nucleotide game has replication, competition, and evolution; all without membranes or proteins.

How will this game play out? Evolution of the Nucleotide Game continues.

copyright © 2004, 2005 Aubrey Jaffer

I am a guest and not a member of the MIT Computer Science and Artificial Intelligence Laboratory.  My actions and comments do not reflect in any way on MIT.
The Game Theory of Life
agj @
Go Figure!