How does the inside of a cell compare to a galaxy?

Both the inside of a cell and a galaxy fall into a stable pattern, with a clear centre. In the natural world, there are lots of stable forms both in biology and physics - unstable things do not last for very long and are infrequently observed. It is said that at the centre of the galaxy there is a black hole and at the centre of a cell there is a nucleus. To some degree the nucleus and black hole control the fate of the galaxy and cell, respectively. However, I feel that this comparison is unjust since the two structures are so incredibly different. I'm not sure that it is useful to compare them.