A Hidden Genetic Code

This isn’t strictly relevant to the usual subject matter of this blog, but it is, nonetheless, of interest to any who would take an empirical approach to studying consciousness. It certainly bears relevance to the newly emerging sub-field of neurogenetics, which I personally believe will reveal a great deal about the structure of the neural correlates of consciousness—especially when it comes to deciphering differences between individuals, as a result of differing underlying neural foundations. It will also be useful, I think, in the broader investigation of molecular evolution. 

The gist of the article, though I would recommend reading it for yourself, is as follows. Proteins are essentially ordered amino acids sequences that can fulfill a particular role based on biochemical properties specific to a given sequence. These sequences are encoded by your genome by ordered sets of codons, or ordered sets of three specific adjacent nucleotides (ex., AAT, AGT, GGT, CAC, etc.). Since there are four nucelotide base pairs used by DNA/RNA, this gives 64 possible codons (i.e., 4 x 4 x 4). There are, however, only twenty amino acids that are encoded by these codons. What this results in is lots of repetition: a single amino acid is often represented by at least four different codons. Why this repetition? One explanation is that if codons were only made up of two adjacent nucleotides (giving codons of AA, AT, AC, AG, etc.), we would only have 16 possible codons (i.e., 4 x 4), so we would unable to code for the remaining 4 amino acids, severely limiting biological function. Thus, the next step up is codons of length 3, allowing all 20 amino acids, and dealing with a bit of repetition. This article, however, proposes a more complete explanation: not all codons for the same amino acid are equally efficacious. If an organism encounters a period of nutrient deprivation, it needs to decrease its energy and resource dependence if it wants to survive until resources are again plentiful. Some codons are naturally able to accommodate this by there limited efficacy. That is, in low-resource situations, these codons are unable to “summon forth” their associated amino acid in order that the already low levels of those amino acids are not totally depleted. This allows an organism to encode proteins that, even though they use the same amino acids, have a “priority” associated with them. Proteins that are essential to survival are encoded by high-efficiency codons, are therefore in the high-priority group, and are thus still created in low-resource environments. Proteins that are less essential, on the other hand, are encoded by low-efficiency codons, are therefore in the low-priority group, and can be automatically “turned off” in low-resource conditions.

What this means for the rest of biology is yet to be seen, but the possibilities are enormous. In the realm of Biological Psychology, and relatedly consciousness research, we may be able to better explain behavioural changes under periods of aforementioned resource scarcity as a result of altered brain chemistry. In Medicine, we can do the same sort of analysis, but at an organ system level, potentially revealing the basis for a number of disease states. The possible ramifications are truly endless.

The original article can be found here. Enjoy!