Mitosis and meiosis are two distinct processes of cell division that result in different types of genetic material outcomes.
Mitosis:
- Purpose: Mitosis is primarily for growth, repair, and asexual reproduction.
- Result: It produces two identical daughter cells, each with the same number of chromosomes as the parent cell (diploid in humans, for example, 46 chromosomes).
- Genetic Makeup: The genetic material in the daughter cells is identical to that of the parent cell. There are no unique combinations of genetic material because crossing over does not occur.
Meiosis:
- Purpose: Meiosis is used to produce gametes (sperm and eggs) for sexual reproduction.
- Result: It results in four non-identical daughter cells, each with half the number of chromosomes of the parent cell (haploid in humans, for example, 23 chromosomes).
- Genetic Makeup: Meiosis introduces genetic variation through two key processes:
- Crossing Over: Homologous chromosomes exchange genetic material during prophase I, leading to new combinations of alleles.
- Independent Assortment: During metaphase I, the orientation of homologous chromosome pairs is random, which results in a mix of maternal and paternal chromosomes in the gametes.
Unique Combinations:
- Mitosis: No unique combinations; daughter cells are clones of the parent cell.
- Meiosis: Unique combinations of genetic material arise due to the processes of crossing over and independent assortment, resulting in genetic diversity among offspring.
In summary, while mitosis produces identical cells, meiosis results in genetically diverse cells that carry unique combinations of genetic material. This diversity is crucial for evolution and adaptation in sexual reproduction.