Prokaryotic nucleoid

 Recent work by a number of workers demonstrated that the network of threads consists of a single chromosome in the form of a ring. The exact three-dimensional arrangement by which 1100μ -1400μ long

DNA chain, which forms 80% of the chromosome by mass (the remaining 20% being protein + RNA), is packed in an lμ long nucleoid, which could also be established now.

At least two proteins, which bind DNA, resemble histones of eukaryotes and organize the DNA into structures comparable to nucleosomes of eukaryotes. It has been shown that the chromosome of E. coli is organized in about 45 loops, which radiate out from a dense proteinaceous scaffold, which is assumed to anchor the DNA. In each of the 45 loops, DNA is supercoiled and complexed with protein. The functional significance of looped domains is not clear but they do not represent units of transcription as in the case of lampbrush chromosomes.