Where is double stranded circular naked DNA commonly observed?

Double stranded circular naked DNA is commonly found in structures such as plasmids, which are prevalent in bacteria. This form of DNA is not associated with histones and is distinct from the linear DNA found in the chromosomes of eukaryotic organisms. In addition to bacteria, circular DNA is also present in the mitochondria and chloroplasts of eukaryotic cells, reflecting their evolutionary origins from prokaryotic ancestors through processes such as endosymbiosis.

In bacteria, the circular naked DNA serves essential functions, including encoding for genes that can be involved in antibiotic resistance or metabolic functions. Similarly, the mitochondrial and chloroplast DNA is circular and plays a critical role in the organelles' own processes, including energy production and photosynthesis. This characteristic of double stranded circular naked DNA being prevalent in these entities illustrates their shared evolutionary heritage and specialized functions within different organisms.