 There are, we suggest, two initially tenable approaches to the  problem.[5]  The first, and one that is often implicitly or explicitly assumed to be correct, is to define the genome as the sequence of nucleotides. This may or may not contain extranuclear DNA, as in mitochondria or chloroplasts; the genome.gov definition explicitly includes the former. This last question figured largely in debates over the moral permissibility of so-called mitochondrial transplants (a designation that speaks volumes, incidentally, about the almost magical importance attached to DNA as opposed to the remaining contents of the cell), but it is not one of great philosophical significance. The alternative approach is to understand the genome strictly as a material object, presumably, in most cases, the nuclear chromosomes. 