What is cell division?
Cell division is the process by which a parent cell divides to form new daughter cells. Before a cell divides, it copies its DNA so that each new cell receives a complete set of genetic information carried on structures called chromosomes.
Two types of cell division
There are two kinds of cell division, and it is important not to confuse them.
| Mitosis | Meiosis | |
|---|---|---|
| Number of divisions | One | Two |
| Daughter cells | 2 | 4 |
| Chromosome number | Diploid (same as parent) | Haploid (half of parent) |
| Main role | Growth and repair | Forming gametes |
Key idea
Mitosis produces 2 diploid cells that are genetically identical to the parent. Meiosis produces 4 haploid cells that are genetically different.
Why cell division matters
- Growth: more cells means a larger organism.
- Repair and replacement: new cells replace damaged or dead ones, such as healing a wound.
- Reproduction: meiosis forms gametes (sperm and ova) for sexual reproduction; some organisms use mitosis for asexual reproduction.
Chromosomes and accuracy
Genetic information is carried on chromosomes, thread-like structures made of DNA found in the nucleus. Before any division, each chromosome is copied so it consists of two identical chromatids joined together. During division these must be shared out exactly, so that each daughter cell receives the correct number and type of chromosomes. If this sharing goes wrong, a cell may end up with too many or too few chromosomes, which can lead to disorders or, in body cells, uncontrolled division such as cancer. Careful, accurate division is therefore essential to health.
Example
When you cut your finger, the skin cells around the wound undergo mitosis. They divide to make new identical skin cells that fill the gap and heal the cut.
Remember
Diploid (2n) cells have chromosomes in pairs; haploid (n) cells have one of each. Human body cells are diploid (46); human gametes are haploid (23).