I know that bacteria does not have a nucleus, and so DNA is dispersed in the cytoplasm. The DNA is arranged in circular plasmids, but the plasmids can also be linear. The DNA is shorter, there are no introns, and so it is more compact compared to the DNA of eukaryotic cells.
As for viruses (which have DNA), DNA is arranged in the capsid. Can be circular or linear. (?...not sure)
Anything else I could add or subtract?
Your help would be appreciated.What is the arrangement of DNA in bacteria and viruses?
For bacteria, it isn't exactly correct to say the DNA is floating about willy-nilly inside the cell. Take a look at http://www.cellsalive.com/cells/bactcell.htm, http://www.ucmp.berkeley.edu/bacteria/bacteriamm.html, and http://biology.kenyon.edu/courses/biol114/Chap01/chrom_struct.html. Each displays the DNA as rather confined but without a detectable membrane separating it from everything else. While you are at it, see if you can find some similarities to mitochondria.
Some viruses have RNA only (influenza, polio), some have DNA intermediates (retroviruses, yellow fever, rubella, west nile). Also there are non-capsulated viruses (parvovirus, reovirus). Virology is a complex world. See the lecture at
http://www.atsu.edu/faculty/chamberlain/Website/Lects/Propert.htm
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