The continuity of cells generating cells (the cell theory), generation after generation, and the view of cells as dynamic genetic systems (Chapter 11), is further developed in this chapter. The details of DNA replication, which precedes cell division, is a central topic, which builds on the Chapter 12 material concerning DNA as the genetic material. The orderly process of cell growth and division are also covered in detail. The concepts of organisms functioning through molecular interactions and of the relationships between structure and function at the molecular level, are stressed.