Introduced into a culture of bacterial cells, extrachromosomes are organelles capable of independently developing outside the nucleus of a bacterial cell or actively moving between cells of the body, consisting of genetic information placed in a DNA molecule independent of chromosomes - a plasmid or bacteriophage. Extrachromosomal factors become active several hours after they enter the cell. Gene plasmids in bacteria are much easier to isolate and study than chromosomal ones.