In complex cells, the genetic material--DNA--is stored in the nucleus, which serves as the cell's control center. When a cell is not dividing, DNA strands look like a ball of entangled threads. But when the cell divides, the DNA strands duplicate and take on the complicated organization of chromosomes. Most bacteria have only one, circular chromosome; but a more complex organism like the Indian fern (Ophioglossum reticulatum), has over 1200. Scientists are using high-powered microscopes to see inside the nucleus of dividing cells to determine what role different DNA arrangements play in cell division and other functions.