Posted: May 17, 2012 1:12 pm
CharlieM wrote:It is certainly not the genome that's doing the organizing. The genome of itself can do nothing and also the same genome sits in the stomach cells and in the skin cells.
Of course the genome does things. The different cellular environments (including the cell membrane) of different cell types produces different gene expression, apart from those genes that are essential to the functioning of the cell itself. In multicellular species, chromosomes have been selected for because they can and do turn most of theose genes that are not essential for a living cell permanently off in any one cell type. Organismal death would be rapid if this failed completely. Thus, the same genome can reliably do different things in different cell types.