"Science says Life begins at conception..."
No, that isn't what 'science' says. The evidence is that life began ~3.6Gya and that HUMAN life BEGAN about 200,000 years ago.
Since that earliest life there has been a continuous chain of decent of one cell to another generation of cell with constant mutation:
The variable somatic genome
Extensive genetic variation in somatic human tissues
From the above, we see that every cellular descendant is somewhat unique, not just at fertilization. You are merely making an arbitrary special pleading case.
And, if you want to claim that it has to be *really unique* to count then you've just failed to account for twins -- does this mean we can kill one twin because the other is nearly genetically identical? Again, you are reduced to special pleading.
Furthermore, we do not define human existence at the cellular level. A human being is trillions of cells working together in concert to create consciousness, at the end of life when the cells are still there but the brain function has ceased, we don't consider it murder to allow the rest of the body to die.
If individual 'human' cells deserved protection as a human being then the trillions of HeLa cells (human cells that are now immortal and live as individual cells) would each be drawing a pension and have the right to vote as they are well over 18.
So... are these single-celled 'humans' the same as a person or not? If not, why not? They are unique, they are human, they are living... what is your criteria?
Furthermore, this idiotic idea that a single-cell at the moment of fertilization magically becomes a 'new human being' would (1) make your God the biggest mass murderer in all of history due to the frequency of spontaneous abortions and (2) simultaneously pin this flaw on the women making her out to be the murderer when there is a miscarriage: http://www.guardian.co.uk/world/2011/jun/24/america-pregnant-women-murder-charges Because of you mentally sick and ignorant people pushing this nonsense.
See more info and related dumb arguments at When Cells Divide: the argument from uniqueness