Which one could produce a sperm with two x chromosomes nondisjunction during meiosis 1 or nondisjunction during meiosis 2?

Answer 1

During meiosis I of a primary spermatocyte (an immature sperm cell that hasn't gone through either round of meiosis yet), the homologous chromosomes are supposed to separate, so the XX and YY chromosomes should separate into two different secondary spermatocytes (I wrote XX and YY since there are two sister chromatids for each chromosome). If non-disjunction occurs here, you'd get an one secondary spermatocyte with XXYY and one with no sex chromosomes (so, that's the answer to your question).

During meiosis II, this sister chromatids separate (i.e. XX separates so that one X is given to each cell, and so on with the rest of the chromosomes). In the XXYY spermatocyte, one copy of X and one copy of Y go to each daughter cell as the sister chromatids separate. This results in two XY spermatids and two spermatids with no sex chromosomes being produced (as long as there isn't another non-disjunction). Then they eventually becoming a mature sperm.

If one of those XY sperm ever makes its way to an egg and fertilizes it, you'd get an XXY zygote (which would usually be viable and always male).

If one of the sex-chromosome-less sperm fertilizes an egg, the zygote would be X0 (female), but probably wouldn't be viable and die in utero.

Answer 2

During meiosis I of a primary spermatocyte (an immature sperm cell that hasn't gone through either round of meiosis yet), the homologous chromosomes are supposed to separate, so the XX and YY chromosomes should separate into two different secondary spermatocytes (I wrote XX and YY since there are two sister chromatids for each chromosome). If non-disjunction occurs here, you'd get an one secondary spermatocyte with XXYY and one with no sex chromosomes (so, that's the answer to your question).

During meiosis II, this sister chromatids separate (i.e. XX separates so that one X is given to each cell, and so on with the rest of the chromosomes). In the XXYY spermatocyte, one copy of X and one copy of Y go to each daughter cell as the sister chromatids separate. This results in two XY spermatids and two spermatids with no sex chromosomes being produced (as long as there isn't another non-disjunction). Then they eventually becoming a mature sperm.

If one of those XY sperm ever makes its way to an egg and fertilizes it, you'd get an XXY zygote (which would usually be viable and always male).

If one of the sex-chromosome-less sperm fertilizes an egg, the zygote would be X0 (female), but probably wouldn't be viable and die in utero.

Answer 3

During meiosis I of a primary spermatocyte (an immature sperm cell that hasn't gone through either round of meiosis yet), the homologous chromosomes are supposed to separate, so the XX and YY chromosomes should separate into two different secondary spermatocytes (I wrote XX and YY since there are two sister chromatids for each chromosome). If non-disjunction occurs here, you'd get an one secondary spermatocyte with XXYY and one with no sex chromosomes (so, that's the answer to your question).

During meiosis II, this sister chromatids separate (i.e. XX separates so that one X is given to each cell, and so on with the rest of the chromosomes). In the XXYY spermatocyte, one copy of X and one copy of Y go to each daughter cell as the sister chromatids separate. This results in two XY spermatids and two spermatids with no sex chromosomes being produced (as long as there isn't another non-disjunction). Then they eventually becoming a mature sperm.

If one of those XY sperm ever makes its way to an egg and fertilizes it, you'd get an XXY zygote (which would usually be viable and always male).

If one of the sex-chromosome-less sperm fertilizes an egg, the zygote would be X0 (female), but probably wouldn't be viable and die in utero.

Answer 4

neither