Most bacterial cells have their genes arranged in a single circle of DNA. The circle of DNA plus some attached proteins is referred to as the bacterial chromosome. Up until quite recently, it was thought that the chromosome in the tiny bacteria cell resembled a tangled ball of yarn. It is now known that multiple factors cooperate to condense DNA into a highly dynamic assembly of supercoiled loops. Although there is variability in the lower levels of chromosome structure, the global arrangement of DNA within the cell is conserved, with individual loci arrayed along the long axis if the cell in line with their order on the genetic map. This order is maintained and propagated during DNA replication. Upon duplication of a given segment of the chromosome, it is immediately released from the replisome (the DNA replication machine) and it moves rapidly to its conserved position in the incipient daughter cell compartment. Partitioning of the bacterial chromosome thus takes place while DNA replication is in progress. Furthermore, it is becoming clear that the bacterial cell is highly organized, presenting new challenges and opportunities for the design of new antibiotics.
For further information see:
http://www.ascb.org/ibioseminars/Shapiro/Shapiro1.cfm
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