DNA is often referred to as the blueprint for life because all living organisms have DNA, including plants. DNA stores the genetic information that links every organism to a common ancestry. Some plants, such as onions and tomatoes, have more DNA than humans.
DNA is wound into spiral-shaped structures called chromosomes. In plants and animals, these chromosomes are stored in cell nuclei. In bacteria and archaea, chromosomes float around freely in the cytoplasm with cells. DNA can be viewed as a code that makes up both plant and animal genes, including humans. In order for evolution to occur, new genes must develop. However, complex organisms may maintain some genes that manage basic metabolic functions from a more primitive period of time.