Question about gamete formation
Hello, can anybody tell me how exactly one cell becomes four sex cells? I understand mitosis makes two identical cells but what about meiosis? How many divisions, what are the main differences and why are the resulting cells not the same? Thanks for any help.
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Sure! Meiosis is special because it produces four haploid gametes instead of two diploid cells. It consists of two divisions: meiosis I and meiosis II. DNA replicates only once before meiosis I. In meiosis I homologous chromosomes separate (reduction division). In meiosis II sister chromatids separate. For a good overview of all steps check this: phases of meiosis. It shows prophase I with crossing over (very important for diversity), metaphase I with random alignment, anaphase I where whole chromosomes move apart, then meiosis II looks similar to mitosis but starts with haploid cells. Final result — 4 non-identical cells with half the chromosomes. This keeps chromosome number constant across generations and creates genetic variation through crossing over and independent assortment.