AST 309L Chapter Notes - Chapter 5: Human Genome Project, Carcinogen, Genetic Code
Document Summary
Chapter 5: the nature of life on earth. If organisms are fairly diferent from earth, we will need clearer guidelines to decide whether or not they are truly living. One way to seek distinguishing features of life is to study living organisms and look for common characteristics. There are 6 key properties shared by most living organisms on earth: order. The materials in living organisms always exhibit some type of order. In logical terms, we say that order is a necessary condition for life, because something cannot be alive without order. However, order is not a suicient condition for life, because order alone does not make something alive. Simple life forms, such as bacteria, reproduce by dividing into copies of themselves. Complex life forms use sexual reproduction, and ofspring inherit genetic material from both parents. There are two borderline cases in which scientist disagree: virus.
