Final answer:
Mitochondria and chloroplasts each have their own replicase to independently replicate their own circular DNA within eukaryotic cells.
Step-by-step explanation:
The eukaryotic nucleus uses two replicases for DNA replication. However, mitochondria and chloroplasts, organelles within eukaryotic cells, each contain their own DNA and replicate it using their own replication machinery. Mitochondria have their own circular DNA, which they replicate independently from the cell's nuclear DNA. Similarly, chloroplasts, found in photosynthetic eukaryotes, also replicate their own circular DNA independently. Both organelles are thought to have evolved from free-living prokaryotic organisms through endosymbiosis, which explains their separate replication mechanisms distinct from the cell nucleus. Therefore, it can be deduced that mitochondria and chloroplasts each have at least one type of replicase for their DNA replication.