Final answer:
The characteristic shared between most prokaryotic and mitochondrial genomes is the presence of a single, circular chromosome.
Step-by-step explanation:
The characteristic shared between most prokaryotic and mitochondrial genomes is the presence of a single, circular chromosome. Prokaryotes, including bacteria, have a circular chromosome in the nucleoid region, while mitochondria in eukaryotic cells also have their own circular DNA chromosome. This similarity suggests that mitochondria were once free-living prokaryotes.