Cells come from pre-existing cells. This principle is a cornerstone of cell theory, which states that all living organisms are composed of cells and that new cells arise only by the division of existing cells. The very first cells on Earth are thought to have emerged about 4 billion years ago through a process involving the formation of self-organized prebiotic macromolecules, eventually leading to living cells capable of replication and evolution. Modern cells continue this lineage by dividing to form new cells in organisms today.
Cells are broadly divided into prokaryotic cells (such as bacteria) and eukaryotic cells (found in animals, plants, fungi). Eukaryotic cells evolved from prokaryotic ancestors through symbiotic relationships, which allowed the development of complex cells with organelles like mitochondria and chloroplasts.
In summary, cells come from the division of existing cells, and the original cells originated from non-living chemical structures transforming into life around 4 billion years ago.
