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When it's completely unraveled, DNA is known to extend approximately six feet in length, yet is somehow able to cram itself into a cell's nucleus. In a study published today (July 27) in Science, researchers created a novel visualization method that revealed a 3-D glimpse of chromatin as it sits jam-packed within the nuclei of human cells. The researchers found that, contrary to how it's depicted in most textbooks, chromatin does not fold in on itself in an organized manner to create distinct structures. Instead, it forms a pliable, inconsistent chain characterized by a wide variety of folding patterns. 

DNA folding model

Questions about the nature of viruses remain quite vexing. Recent studies of the giant Mimivirus illustrate this point. Its large size and correspondingly large genome test our general ideas of viruses as small, simple entities. The existence of genes associated with translation, metabolism, DNA repair, and protein folding raises questions about the evolutionary history of viruses. Further studies of this virus, and the search for other giant viruses, may shed light on these issues.