Final answer:
A double-stranded DNA genome is found in both cells and certain viruses, including the Group I viruses. Cells have a double-stranded DNA genome, while the genomes of viruses can vary and include single-stranded DNA, double-stranded DNA, or RNA, contributing to their infectious capabilities.
Step-by-step explanation:
The double-stranded DNA genome is found in both cells and viruses. In biology, the term, genome, refers to all genetic material of an organism. In cells, the genome is typically found within the nucleus in eukaryotes, or in the nucleoid in prokaryotes, and is composed of double-stranded DNA. This includes not only the cellular organisms like humans, plants, and bacteria, but also certain viruses which are referred to as Group I viruses. These viruses use double-stranded DNA similar to that of cellular hosts.
Furthermore, while some viruses replicate using the standard flow of genetic information from DNA to RNA to protein, other types possess RNA genomes or single-stranded DNA. For instance, retroviruses have an RNA genome that is reverse-transcribed into DNA and integrated into the host genome, which is why retroviral DNA rather than single-stranded or double-stranded DNA or RNA viral genomes is found in host DNA. The diversification in viral genome types allows viruses to infect a wide range of hosts and adapt to various environments, which is a fundamental aspect of their survival and evolution.