Scientists reveal hidden structures in bacterial DNA
(PHYSorg.com Biology)

DNA contains the instructions for life, encoded within genes. Within all cells, DNA is organised into very long lengths known as chromosomes. In animal and plant cells these are double-ended, like pieces of string or shoelaces, but in bacteria they are circular. Whether stringy or circular, these long chromosomes must be organised and packaged inside a cell so that the genes can be switched on or off when they are required.