<Ol> <Li> All living organisms are composed of one or more cells . (However, this is considered a controversy because non-cellular life such as viruses are disputed as a life form . See Non-cellular life .) </Li> <Li> The cell is the basic unit of structure and organization in organisms . </Li> <Li> Cells arise from pre-existing cells . </Li> </Ol> <Li> All living organisms are composed of one or more cells . (However, this is considered a controversy because non-cellular life such as viruses are disputed as a life form . See Non-cellular life .) </Li> <Li> The cell is the basic unit of structure and organization in organisms . </Li> <Li> Cells arise from pre-existing cells . </Li>

The idea that all living things are composed of cells and that all cells come from other cells