Random Assortment

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•  Orientation of pairs of homologous chromosomes prior to separation is random

During metaphase I, homologous chromosomes line up at the equator as bivalents in one of two arrangements:

  • Maternal copy left / paternal copy right  OR  paternal copy left / maternal copy right

This orientation of pairs of homologous chromosomes is random, as is the subsequent assortment of chromosomes into gametes

  • The final gametes will differ depending on whether they got the maternal or paternal copy of a chromosome following anaphase I

As this random assortment will occur for each homologous pair, the number of possible gamete combinations are dependent on the number of homologous pairs

  • Gamete combinations = 2n (where n represents the haploid number)

Random Assortment of Homologous Chromosomes

random assortment