Science
Meiosis.
Definition
Meiosis is a type of cell division that produces four genetically unique haploid cells (gametes) from one diploid parent cell. It involves two rounds of division (meiosis I and meiosis II) and is essential for sexual reproduction, introducing genetic variation through crossing over and independent assortment.
How it works · 5 phases
Step by step.
- DNA replicates during interphase, producing duplicated chromosomes.
- In meiosis I, homologous chromosomes pair up and crossing over occurs during prophase I.
- Homologous pairs separate during anaphase I, reducing chromosome number by half.
- In meiosis II, sister chromatids separate, similar to mitosis.
- Four genetically unique haploid daughter cells are produced.
Examples
Real-world.
- 1 Human egg and sperm cells each containing 23 chromosomes
- 2 Crossing over creating new allele combinations on chromosomes
- 3 Independent assortment producing 2²³ possible gamete combinations in humans
Key Fact
Meiosis produces 4 haploid cells (n) from 1 diploid cell (2n).