blastomeres

It seems to me that the first decisive issue to face is the one that the NYTimes attributes to Senator Brownback's office: that excising a cell from the early embryo is the equivalent of artificially-induced twinning, and thus to stop that excised cell from developing is to take the life of a new human individual (even assuming that the original embryo is wholly unharmed). This is very worrisome to me, but I really don't know enough facts to reach a clear judgment. For example, is the excised cell fully totipotent, like an embryo, or only pluripotent, like the sorts of stems cells that are usually sought? And even if it is totipotent, has that potency been ACTIVATED, so that we must say that a new life is underway? (Or is asking this last question bad to begin with, because it tries to draw too fine a line?)