By definition, a cell is the fundamental and structural unit of all living organisms. The principles are... See full answer below. The modern cell theory expands this: 4) Energy flow occurs within cell 5) Cells contain hereditary information (DNA) and it is passed from one cell to another 6) All the cells have basically similar chemical composition Cells both make up all living things and run the processes needed for life. Simply put, modern cell theory says that all organisms alive on the Earth are made up of cells; all life consists of one or more cells, and new cells form when old cells divide. Each part of a cell has a different function, and your cells are responsible for taking in nutrients, turning nutrients into energy, removing … Modern cell theory is a set of principles regarding how cells work that help us as we learn more about the specifics of cells. Cell theory definition, a basic tenet of modern biology, first stated by Matthias Schleiden and Theodor Schwann in 1838–39, that cells are the basic units of structure and function in living organisms… are all made up of cells. Your hair, skin, organs, etc. Cells. The cell theory definition states that cells are the building blocks of life. Cell theory definition is - a theory in biology that includes one or both of the statements that the cell is the fundamental structural and functional unit of living matter and that the organism is composed of autonomous cells with its properties being the sum of those of its cells. In fact, each person is estimated to be made up of nearly 40 trillion cells! Cells are the fundamental building blocks that make up all life, and all life begins as a single-celled organism. It is the smallest biological, structural and functional unit of all plants and animals.Therefore, cells are called the ‘Building Blocks of Life’ or the ‘Basic units of Life’. 2) Cell is the basic structural and functional unit of life 3) All existing cells are arrived from pre-existing cells by division.