1. All living organisms are composed of one or more cells. This means that cells are the basic unit of life, and all living things are made up of them.

2. The cell is the basic unit of structure and function in living organisms. This means that cells are not just building blocks, but they also carry out all the essential processes of life, like metabolism, growth, and reproduction.

3. All cells arise from pre-existing cells. This means that cells do not spontaneously generate, but instead come from other cells that divide.

These three parts form the foundation of our understanding of life and how it works.