The cell theory says that:
- All organisms are composed of one or more biological cells.
- The cell is the basic unit of organization of organisms.
- All cells come from preexisting cells.
There are two basic types of cells:
- prokaryote: do not have a nucleus or membranes surrounding its organelles. Example: bacteria.
- eukaryotes: do have a nucleus and organelles with membranes surrounding them. Example: plants, animals.