holds an organism's hereditary information
DNA, or deoxyribonucleic acid, is the hereditary genetic material for most living organisms. DNA is present in cells in the form of a double-stranded helix that is composed of long strands of nucleotides. The unique sequence of nucleotides within the DNA molecule stores the genetic information. process by which an organism is genetically changed, resulting in a mutation, which is a change in the DNA sequence of a gene. It may occur naturally, for example, due to natural exposure to ultraviolet (UV) light or chemicals; or it can happen deliberately for the purpose of increasing genetic variation of a species.