False-colour transmission electron micrograph of the bacterium Escherichia coli. The bacterial cell in the centre of the picture was treated with an enzyme to weaken its wall, then placed in water, causing its DNA to be ejected. The DNA is visible as the gold coloured fibrous mass lying around the bacterial shell. The length of the DNA is 1.5 millimetres or 1000 times the length of the cell from which it came. E.coli is usually an harmless inhabitant of the human intestinal tract. It is a major laboratory organism & much of the understanding of genetics has come from the study of this bacterium. Magnification: x7850 at 35mm, x15,700 at 6x7cm size.