The three main ideas (or concepts) of the cell theory are:
1. All living things are made of one or more cells.
2. The cell is the basic unit of life in which the activities of life occur.
3. All cells come from cells that already exist.
The 3 main ideas of the cell theory is: 1. all living things are composed of cells 2. cells are the basic units of structure and function in living things. 3. all cells are produced from other cells.