What characterizes meiosis?

Meiosis is characterized by two sequential division processes, known as meiosis I and meiosis II, which ultimately result in four cells. Importantly, these cells are haploid, meaning they contain half the number of chromosomes compared to the original diploid cell from which they were derived. This reduction in chromosome number is crucial for maintaining the stability of the species' chromosome count across generations, especially during sexual reproduction when two haploid gametes unite.

The first division, meiosis I, separates homologous pairs of chromosomes, halving the chromosome number. The second division, meiosis II, is akin to mitosis and separates the sister chromatids of each chromosome, resulting in four distinct cells. Each of these cells is genetically varied due to the processes of crossing over and independent assortment that occur during meiosis, contributing to genetic diversity.

This unique feature of producing four cells with half the original chromosome number distinguishes meiosis from mitosis, which produces two genetically identical diploid cells. By understanding this, one appreciates how meiosis is fundamental not only to gamete formation but also to the principles of inheritance and variation in living organisms.