Mitosis and meiosis I are both forms of cell division, but they differ significantly in their processes and outcomes. Here are four crucial differences:
1. Daughter Cell Ploidy
- Mitosis: Results in two daughter cells that are diploid (2n), meaning they have the same number of chromosomes as the parent cell. The chromosome number remains constant.
- Meiosis I: Results in two daughter cells that are haploid (n), meaning they have half the number of chromosomes as the parent cell. The chromosome number is halved. This is achieved through the separation of homologous chromosome pairs.
2. Genetic Identity of Daughter Cells
- Mitosis: Produces daughter cells that are genetically identical to each other and to the parent cell. This is because during mitosis, the chromosomes are duplicated and then separated equally into two identical sets.
- Meiosis I: Produces daughter cells that are genetically different from each other and the parent cell. This is due to crossing over (recombination) during prophase I and independent assortment of chromosomes during metaphase I.
3. Tetrad Formation (Synapsis)
- Mitosis: Tetrad formation (also called synapsis) does not occur during mitosis. Homologous chromosomes do not pair up.
- Meiosis I: Tetrad formation is a defining characteristic of prophase I. Homologous chromosomes pair up to form tetrads (also called bivalents). This pairing allows for crossing over to occur.
4. Separation of Chromosomes
- Mitosis: Sister chromatids are separated during anaphase. Each daughter cell receives a complete set of single-stranded chromosomes.
- Meiosis I: Homologous chromosomes are separated during anaphase I. Sister chromatids remain attached. Each daughter cell receives one chromosome from each homologous pair, but each chromosome still consists of two sister chromatids. The sister chromatids are separated during Meiosis II.
In summary, mitosis creates identical diploid cells for growth and repair, while meiosis I is the first step in a two-part process that generates genetically diverse haploid cells for sexual reproduction.
