In the past, I have floated the hypothesis of molecular threaders, which are ring structures that can interact with polymers to unfold them, in essence translating the rotary motion inherent in a wheel to the linear unfolding (and thus threading) of a polymer. As I explained:

What all these proposed wheels have in common is that they form ring structures and handle polymers in an ATP dependent fashion. I’ll label these machines as the molecular threaders. In a sense, cells do have “cog wheels,” only they are more sophisticated than Paley’s watch.

Above, I noted the advantage of a rotary motion device is that it can carry out such work indefinitely with minimal rearrangement of the surrounding structural architecture. Yet the cell is also very good at coordinating internal structural rearrangements, as its order is dynamic. Thus, the advantage of the wheel inside the cell may be minimal and restricted to certain functions. This is one reason why I propose the molecular threaders. The rapid threading of polymers is something a wheel could do very well.

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The non-teleological perspective views RNA as a primitive, ancient relic of the process of abiogenesis. The teleological perspective views RNA as a sophisticated molecule that plays an essential control function within the cell and has never existed apart from its cellular context.

While RNA is crucial to all living things, I think eukaryotes have more fully exploited its ability to control the proteome (a cell’s protein complement). A simple fact from cell biology explains this. In prokaryotes, the process of RNA synthesis (transcription) is coupled to the process of protein synthesis (translation). This allows bacteria to more efficiently express their genes and the bacterial cell design is all about efficiency. But eukaryotes trade efficiency for flexibility, and as such, have a nucleus where the genome is physically separated from the ribosomes. This means there is a much larger window of opportunity to process and modify protein-encoding RNA in eukaryotes, which in turn means the greater potential for control. One such control mechanism exploited by eukaryotes is alternative-splicing, where a single gene can give rise to dozens of gene products that are variations on a theme.

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