Mitosis Vs Meiosis¶
This page compares the two main types of cell division in AS Biology. They share some stage names and both begin after DNA replication, but they solve different biological problems.
The Big Difference¶
| Feature | Mitosis | Meiosis |
|---|---|---|
| Main purpose | Growth, repair, asexual reproduction | Production of gametes |
| Number of divisions | One | Two |
| Number of daughter cells | Two | Four |
| Chromosome number in products | Same as parent cell | Halved |
| Genetic similarity | Genetically identical | Genetically varied |
What Mitosis Does¶
- Mitosis keeps the chromosome number constant.
- It is useful when a multicellular organism needs more cells that behave like the existing tissue.
- The key outcome is stability: new cells have the same genetic information as the parent cell.
- This is why mitosis is linked to growth and tissue repair.
What Meiosis Does¶
- Meiosis produces haploid cells for sexual reproduction.
- The chromosome number is halved so that fertilisation can restore the diploid number.
- The key outcome is variation. Independent assortment and crossing over create new combinations of alleles.
- This matters because variation is the raw material for natural selection.
Where Students Mix Them Up¶
- DNA replication happens before both processes, but only meiosis has two nuclear divisions.
- Mitosis does not create variation in the same deliberate way that meiosis does.
- Meiosis is not just "mitosis twice". The pairing of homologous chromosomes and the reduction in chromosome number make it fundamentally different.
Memory Shortcut¶
- Mitosis means maintenance.
- Meiosis means mixing and making gametes.