Dr. Cecil Fox/National Cancer Institute
Cells are the fundamental units of life. Whether they be unicellular or multicellular life forms, all living organisms are composed of and depend on cells to function normally. Not all cells however are alike. There are two primary types of cells: prokaryotic cells and eukaryotic cells. Eukaryotic cells have a true nucleus (distinct area that houses DNA) and are generally more complex than prokaryotic cells. Examples of eukaryotic cells include animal and plant cells. Bacteria and archaeans are prokaryotic cells. Some interesting facts about cells include:
- There are anywhere from 75 to 100 trillion cells in the body.
- There are more bacterial cells in the body than human cells.
- Prokaryotes are the most primitive forms of life on earth.
- Cells have varying life spans.
- Cells commit suicide.