The definition of life.

Life is defined as a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased, or else because they lack such functions and are classified as inanimate. The question of whether or not viruses and prions are alive is being debated among the scientific community. In my research of this question I saw that most people do not consider viruses to be alive becuase they are not made up of cells or even a single cell, it is simply RNA or DNA inside a protien coating. One man said this about prions, "No, I wouldn't class them as being alive as they're unable to change their structure through changes in the way they're made - there's no genetic code etc - it's just their influence on existing proteins that causes them to misfold and create more prions. There's no opportunity for novelty to arise."