All protocellular organisms contain DNA. DNA is always located in chromosomes. Hence it is called chromosomal DNA. Chromosomes are also called nuclear DNA as they are located in the nucleus. Circular DNA is present in the mother body of mitochondria and in the stroma of chloroplasts.
Protocellular organisms Bacteria and cyanobacteria (blue green algae) contain circular nucleoid DNA and plasmid DNA in their cytoplasm. Such DNA molecules do not contain histone proteins.
Viruses such as vaccinia, variola, adeno herpes simplex, T2, TIV, ϕX174, M13, CMV etc. contain DNA. Smallpox, chickenpox and herpes viruses contain DNA.