I printed out an interesting paper by Delebecque et al. in the journal Science about a week ago and now I have got round to reading it. It is really rather impressive, they are assembling structures in cells, or more accurately getting the cells to express carefully engineered RNA molecules that spontaneously assemble into scaffolds actually inside the cells. RNA is a cousin of the better known DNA molecule. The structures are on the nanoscale, i.e., maybe 10 nanometres across, where a nanometre is a billionth of a metre.

I should say that all cells, including the cells that make up our bodies are absolutely full of scaffolds similar to the ones that Delebecque et al. have designed, although the natural ones are usually made of protein not RNA.

The reason for this is simple: cells need them, and they need them because cells are tiny computers. For example, as our bodies developed before we were born we started off as just a ball of cells, but then one set of cells by exchanging signals with other cells, computed that they are in what should be the tip of the elbow, so the cells then had to compute the appropriate response: develop into the skin cells that you need to cover your elbow.

Other cells computed that they were in the meat of your arse, and so developed into muscle cells. Cells really do need to tell the difference between your arse and your eblow, otherwise the developing embryo will not develop either an arse or an elbow.

Anyway, in fact cells must do a lot of parallel computing, at the same time they need to compute what type of cell they need to be, as well as compute whether or not they have enough oxygen, etc. If they don’t have enough oxygen they give off a distress signal that promotes new growth of a capillary to bring more oxygen.

So cells need to compute in parallel and this brings with it the risk of all these computations getting mixed up, of say a low-oxygen signal getting mixed up with a become-a-muscle-cell signal. One of the ways cells avoid this and compute efficiently in parallel is to make scaffolds and hang a bunch of the machinery to do one computation off one scaffold in one part of the cell, while another bit of computing machinery hangs of another scaffold elsewhere in the cell.

This is a bit like your laptop having a CPU on one part of its motherboard and the graphics chip on another separate part. Then the two chips don’t interfere with each other.

These natural scaffolds strewn all over your cells are typically more sophisticated than the relatively crude structures in the Science paper, but it is a good start. Nature is much better at Lego™ on nanometre (= a billionth of a metre) scales, but maybe we are catching up.