Cellular Creativity and the Unselfish Gene
One of the greatest wonders in the known Universe is the eukaryotic cell. Once thought to be a simple blob of protoplasm, the brilliant work of modern biochemists has shown that...
“A living cell is a self-assembling, self-adjusting, self-perpetuating isothermal system of organic molecules which extracts free energy and raw materials from its environment.
It carries out many consecutive organic reactions promoted by organic catalysts which it produces itself. It maintains itself in a dynamic steady state, far from equilibrium with its surroundings. It functions on the principle of maximum economy of parts and processes. Its nearly precise self-replication through many generations is assured by a self-repairing linear coding system”. (Lehninger, Principles of Biochemistry p12)
How could the blind forces of Nature have created an entity of such incredible complexity and fantastic efficiency?
I would like to suggest a model that may make comprehensible the causal mechanism for the evolution of the design-like structures and processes of the eukaryotic cell.
For reasons that will become apparent, I have called this model ”the Eureka Hypothesis’. The model consists of three parts:
1) Intracellular Biochemical Pathway Selection.
2) Cellular Experimentation.
3) Intercellular Gene Transmission.
Intracellular Biochemical Pathway Selection
Intracellular Biochemical Pathway Selection is a simple consequence of the fact that the eukaryotic cell functions on the principle of maximum efficiency of parts and processes. Assume a new, unique enzyme is expressed by the genome of a living cell. Assume also that the new enzyme catalyses the last step of a biochemical reaction to produce a useful current biomolecule, and that the new pathway synthesizes the biomolecule with greater efficiency. The ”newly discovered’ pathway will automatically be selected, since the new pathway effectively ”short-circuits’ the less efficient pathway. This will occur even if the new process requires more steps than the less efficient pathway.
Thus, a simple, less efficient pathway will be ”short-circuited’ by a more efficient, but more complex pathway. This means that complex biochemical pathways can form in a cell if there is some system for introducing new, unique macromolecules into the biochemical system. Where might these new macromolecules come from?
Cellular Experimentation
The Eureka Hypothesis postulates the existence of a special ”experimenter’ gene in the genome. When each new cell forms, the experimenter gene constructs a new gene at a specific site (the ”signature’ site). After removing the previously unsuccessful signature gene from this site, the experimenter gene selects a random sequence of introns and exons from an existing chromosome for the new signature gene.
The signature gene, when expressed as a polypeptide chain forms a new and unique ”test protein’ which interacts with the rest of the cellular machinery.
Each cell is thus provided with the standard genome for the organism, plus one unique protein encoded in the signature gene. Of course, there is very little probability that any particular test protein will increase the overall efficiency of the cell it occurs in. The cell is already so intricately finely tuned that the vast majority of test proteins will have either no effect or a detrimental effect. But when we consider that there are 10exp14 cells in one human body, and 6.2exp9 people now on Earth, then we realise there are a total of 600,000,000,000,000,000,000,000 independent, unique experiments in human cellular physiology occurring right at this instant.
This means that even if there is only one chance in a hundred thousand million trillion of the test protein having the effect of increasing overall cellular efficiency, then around six such new proteins will occur in today’s human cellular population.
These rare ”successful’ tests will be called 'Eureka events'.
A cell that has undergone a Eureka event is operating more efficiently than the cells that surround it. We will assume this is recognized, either by the Eureka cell itself, or by the cells that surround the Eureka cell. (Presumably by the difference in the basal metabolic rate of the Eureka cell as compared to the surrounding cells). Perhaps the Eureka cell receives chemical ”congratulations!’ signals from the surrounding cells, and on receiving enough of these signals it yells “Eureka!!”.
Intercellular Gene Transmission
When a cell yells “Eureka!!”, it undergoes a radical transformation.
The virus producing subsystem of the cell is activated, and the test gene at the signature loci is copied and packaged into protein coats for distribution to other cells. A cell that is producing viruses also secretes small quantities of the virus inhibiting biomolecule interferon. When interferon binds at the receptor site of an ”uninfected’ cell, it is sending a message to that cell that says “when you receive the incoming viral message, don’t produce more viruses, just write my message into your genome”. Cells that have not received the interferon message begin synthesizing more viruses, in addition to more interferon.
In this way, the organism sacrifices some of its cells to edit the new gene into the genomes of the rest.
In common editing viruses, such as colds and ”flu, viruses are embedded in mucous in the nose and throat, which is then atomized and forcibly sprayed into the air to facilitate the spread of the good news to other people (finally making it understandable why we bless people who sneeze on us!).
In this way, the efficiency improvement, the discovery of one single cell becomes part of the genetic machinery of every cell in the population.
After the new gene has been edited into the genome, the ”immune’ system finally clears away and recycles the debris of protein coats left by the editing viruses.
Note that random mutations play no part in the process. The random element is introduced in an orderly and controlled manner by the cell itself.
So, if the Eureka Hypothesis is correct, every time you ”catch a cold’, viruses from a Eureka event in someone are editing a new, more efficient cellular process into your genome. After every cold, your cells are just a little more complex and efficient.
If the hypothesis is correct, you can think of yourself as a super-biocomputer carrying out a hundred million billion empirical organic calculations simultaneously.
It is by these empirical experiments that cells have discovered the most efficient processes. It is by viral transmission that the blueprints of proteins enhancing cellular efficiency are communicated to other cells of the species.
In this way, the intricate design-like structures and processes of eukaryotic cells have been, and are continuing to evolve, molecule by molecule, in every living organism.
Released from PNT. --Admin
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