system
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human
Mitosis: Which is the Original?

When a cell divides by mitosis, could it be said that either of the two daughter cells produced is the 'original' cell?  Or would it be better to say that the original cell no longer exists and has been replaced by two brand new cells?
I understand this may be more a chicken-and-egg style philosophical question, but I was curious if there are any biological markers distinguishing one daughter cell from the other that could be used to declare one as being 'the original' and one as 'the clone'.
gpt
When there was still active discussion about DNA replication, there was a famous experiment (the Meselson-Stahl experiment) where cells were grown in media that only contained the N15 isotope of nitrogen. This meant all the nitrogen in the DNA was N15 instead of the more common N14.

Then the cells were put in regular N14 media so that all the new DNA strands would have a different mass than the old ones. They used this difference in masses to measure how much dna was old versus new. What they found was what we have come to know about DNA replication--that each cell gets half of the original DNA.

There's still plenty of research in the "symmetry" of mitosis, however.  Turns out proteins and organelles in the cell don't always split 50-50 into the new cells, and this can change the fate of the daughter cells. We use similar tricks to measure how proteins segregate, although it's more common to use fluorophore labeling instead of isotope labeling these days. 

In the case of stem cells, the daughter most similar to the parent cell may keep more of its chromatin-related proteins than the other, as one example, and this means it will have different gene regulation than its sister cell.