Final answer:
A possible hypothesis for the observation of a DNA mutation being passed to only one daughter cell could involve the timing of mutation occurrence, potentially after the DNA mismatch repair mechanism has ceased to be active, leading to the propagation of the mutation in subsequent cell divisions.
Step-by-step explanation:
In the scenario where a DNA mutation is passed on to only one of two daughter cells during mitosis, a plausible hypothesis could relate to the timing of the mutation in relation to the cell cycle. Given that during DNA replication, proofreading mechanisms correct most errors but some may escape repair, if the mutation occurs late in the cell cycle, after mismatch repair enzymes have already acted or are no longer active, the mistaken base might get overlooked. Consequently, when mitosis ensues and cells divide, one daughter cell could inherit the uncorrected mutation while the other does not if the replication fork with the mutation has not yet been fully processed or if the cell has already begun the process of division before repair can occur. These observations underscore how mutations become part of the genome and can potentially affect only a subset of cells after division.