How does meiosis create haploid cells from diploid cells?

Meiosis creates haploid cells from diploid cells through two rounds of cell division, reducing the chromosome number by half.

Meiosis is a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell. This process is crucial for sexual reproduction and contributes to genetic diversity. It involves two successive cell divisions, meiosis I and meiosis II, each of which consists of several stages.

In meiosis I, the diploid parent cell undergoes DNA replication, resulting in two copies of each chromosome, known as sister chromatids. These chromatids are then separated into two new cells during the first cell division. However, unlike in mitosis, the sister chromatids remain together. Instead, homologous chromosomes - one from each parent - pair up and exchange genetic material in a process called crossing over. This leads to recombination, which is a major source of genetic variation. The homologous chromosomes are then separated into two new cells, each of which is now haploid, containing one set of chromosomes.

In meiosis II, the sister chromatids within each of the haploid cells are separated, resulting in four haploid daughter cells. These cells each contain one copy of each chromosome, and thus half the number of chromosomes as the original parent cell. This reduction in chromosome number is crucial for sexual reproduction, as it allows the fusion of two haploid cells - an egg and a sperm - to create a new organism with the correct number of chromosomes.

In summary, meiosis creates haploid cells from diploid cells through two rounds of cell division, reducing the chromosome number by half. The process involves DNA replication, pairing and separation of homologous chromosomes, and separation of sister chromatids. This not only ensures the correct number of chromosomes in sexually reproducing organisms, but also contributes to genetic diversity through recombination.