1. All living organisms are composed of one or more cells. This means that cells are the fundamental building blocks of life. Everything that is considered alive is either a single cell (like bacteria) or is made up of many cells working together.

2. The cell is the basic unit of structure and function in living organisms. This means that cells are not only the building blocks of life but also perform all the essential functions of life. They take in nutrients, convert energy, grow, reproduce, and respond to their environment.

3. All cells arise from pre-existing cells. This means that cells do not spontaneously arise from non-living matter. They are created by the division of existing cells.

These three points form the core of our understanding of life and are fundamental to the study of biology.