In what could be a major realization about the way the human nervous system is formed, scientists at the University of California San Diego have elaborated on earlier work and last week reported that not all brain cells contain a complete set of 46 human chromosomes (two pairs of 23). Each chromosome holds only a part of the genes required to make an organism, and a complete set is refered to as the genome. The entire genome was previously believed to exist in every cell of an organism and is required to make the entire organism…or a clone. This discovery implies that brain cells could not be used to produce clones as other body cells like breast cells were used to create the sheep clone Dolly. The UCSD discovery fits in with previous reports that brain genes are concentrated on certain chromosomes. A majority of genes are believed to be associated with brain function and identifying them is an ongoing effort in humans as well as other apes.