Definition and Explanation
Mitosis and meiosis are two types of cell division processes in eukaryotic organisms.
- Mitosis produces two genetically identical daughter cells from a single parent cell. It is used for growth, repair, and asexual reproduction.
- Meiosis produces four genetically unique daughter cells, each with half the number of chromosomes of the parent cell. It is essential for sexual reproduction and generates gametes (sperm and eggs).
- Mitosis creates two identical diploid cells; meiosis creates four unique haploid cells.
- Mitosis is for growth and repair; meiosis is for sexual reproduction.
- Meiosis introduces genetic variation through recombination and independent assortment.
The main differences are in the number of divisions, chromosome number in daughter cells, and genetic variation.
Worked Example: Chromosome Number Change
Suppose a human cell (diploid, $2n = 46$ chromosomes) undergoes mitosis and meiosis. ### Mitosis 1. **Start:** Parent cell has $2n = 46$ chromosomes. 2. **Division:** One round of division. 3. **Result:** Two daughter cells, each with $2n = 46$ chromosomes (identical \to parent). ### Meiosis 1. **Start:** Parent cell has $2n = 46$ chromosomes. 2. **First Division (Meiosis I):** Homologous chromosomes separate. 3. **Second Division (Meiosis II):** Sister chromatids separate. 4. **Result:** Four daughter cells, each with $n = 23$ chromosomes (haploid, genetically unique). **Summary Table:** | Process | Number of Divisions | Daughter Cells | Chromosome Number | Genetic Identity | |-----------|---------------------|---------------|-------------------|----------------------| | Mitosis | 1 | 2 | $2n$ (diploid) | Identical | | Meiosis | 2 | 4 | $n$ (haploid) | Unique (variation) |