epigenetics

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I'd been thinking of epigenetics as the influence of environment on genetic expression, but that's not right.  At least -- not if I think of "environment" as what's going on outside an organism.....

We all begin from one cell, which divides and divides, and then all those cells grow and divide, and turn into all the different kinds of cells in our bodies, and keep on growing and dividing and growing, until we turn into ourselves.

Each of our cells contains our personal genome.  The SAME genome in each of our cells.

So how is it that bone cells are bone cells, and liver cells are liver cells, and blood cells are blood cells, if they all have the same genetic material?

Epigenetics, that's how.  It's epigenetic info that tells a bone cell to be a bone cell (not a liver cell or a blood cell).............

I learned about epigenetics in What A Plant Knows, in the context of the way plants can react to environmental stress and pass adaptations to that stress along to their offspring.  I was clueless about epigenetics being in play, all the time, in every cell (telling a cell to be a leaf cell rather than a root cell, say.......).  It makes perfect sense, but I never thought of it...........

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