Meiosis and Genetic Variation

While mitosis produces identical cells for growth and repair, sexual reproduction requires a different kind of division. Meiosis is a specialized process that produces gametes (sex cells) and generates the genetic variation that fuels evolution.

Why Meiosis Is Necessary

Body cells are diploid, meaning they contain two copies of each chromosome, one inherited from each parent. In humans this is 46 chromosomes, arranged as 23 homologous pairs. If two diploid gametes fused during fertilization, the chromosome number would double every generation. Meiosis solves this by halving the chromosome number, producing haploid gametes with only 23 chromosomes. When two haploid gametes fuse, the diploid number is restored.

Meiosis involves one round of DNA replication followed by two rounds of division,