During metaphase I, homologous chromosomes line up at the equator as bivalents in one of two arrangements:
This orientation of pairs of homologous chromosomes is random, as is the subsequent assortment of chromosomes into gametes
As this random assortment will occur for each homologous pair, the number of possible gamete combinations are dependent on the number of homologous pairs
- 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)