Meiosis I in Spermatogenesis, recombination

[dli42395]

Primary spermatocytes become secondary spermatocytes through meiosis I, but I'm confused about how recomination happens during this. How does recombination work if primary spermatocytes only have paternal genetic material?

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[kadler538]

I think you're confusing parental genetic material with paternal genetic material. Primary spermatocytes are 2n, aka diploid. Therefore, they have 46 chromosomes and can undergo Meiosis I to become haploid secondary spermatocytes. After this, the secondary spermatocytes undergo another round of Meiosis II to become haploid spermatids. It's the spermatids and then finally the spermatazoa that are haploid with n chromosomes, and that will contain only the paternal info that will be passed on during fertilization.

 

[aldol16]

To add on to the excellent explanation above, recombination can occur with only "paternal" genetic material. Remember, your father also has diploid germ cells before meiosis. So when the chromosomes line up during metaphase I, you have homologous pairs lined up side by side. These homologous pairs are derived from your paternal grandparents. In other words, your father's mother gave him one of those chromosomes and your father's father gave him the other. So when crossing over occurs, the gene(s) are crossing over between this homologous pair. Then anaphase occurs and you get haploid cells.