C. elegans nerve system is labeled with GFP to show the neuronal interconnectivity. C. elegans has a simple and well-defined nerve system that includes 302 neurons. See also more information on C. elegans neuron research. Courtesy of the C. elegans Worm Art Show.
In eukaryotes, the structural unit of the genetic material consisting of a single, linear double-stranded DNA molecule and associated proteins wrapped into a high order structure. During mitosis, chromosomes condense into compact structures visible in the light microscope. In prokaryotes, a single circular double-stranded DNA molecule constitutes the bulk of the genetic material.