[RS]

"The embryo is genetically human and alive or it's not. "

... and since YOUR definition of alive appears to be that of an egg that now has the potential to divide ( vs. an egg that does not ) your circular logic works well.

[MHGinTN]

If/when the 'egg' divides, it is no longer an egg ... but you knew that, you're just trying to obfuscate, trying to create a 'reasonable doubt' that an individual human embryo is in fact an individual human being at that individual's earliest age along the continuum that is its lifetime as it expresses its individuality, its uniqueness. Science tells us that there is no 'reasonable doubt'. The tests devised by scientists, in which they test the amniotic fluids of the individual (not the mother, the individual that built the placenta and filled the sac), those tests work as predicters for the individual because the tests are dealing with an already alive, self-expressing individual human being at the age of embryo, or fetus.

[hocndoc]

The Bioethics Council report covers much of this.
Another guide to decide "when life begins" would be to observe the procedure in the cloning lab or in an in vitro fertilization clinic. The technitions and physicians know which cells are "alive" and which are not.