1. All living organisms are composed of one or more cells. This means that cells are the fundamental building blocks of life.

2. The cell is the basic unit of structure and function in living organisms. Cells carry out all the processes necessary for life, such as metabolism, reproduction, and response to stimuli.

3. All cells arise from pre-existing cells. This means that new cells are not spontaneously generated, but rather are produced by the division of existing cells.