Genes are what life forms use to pass on traits to their offspring. They contain information on how to build organisms and their parts; they are activated or expressed as needed. Genes can get modified (mutations), and they can duplicated and rearranged and recombined, producing more variety of gene combinations. Gene duplication enables the production of genes with additional functions, because the original can get specialized in one direction and a copy specialized in another direction. Genes are often packaged in chromosomes, and chromosomes can split and join and get duplicated. The total set of an organism's genetic information is its genome, and sometimes whole genomes can get duplicated.