What difference does it make whether nondisjunction occurs during meiosis I meiosis II?
Nondisjunction can occur during meiosis I and meiosis II, resulting in abnormal chromosomes number of gametes. The key difference between nondisjunction in meiosis 1 and 2 is that during meiosis 1, homologous chromosomes fail to separate while in meiosis II sister chromatids fail to separate.
Which of the following describes the gametes produced if nondisjunction occurs during meiosis I?
If nondisjunction occurs during meiosis I, homologous chromosomes fail to separate. … Offspring from this cross would be triploid and produce gametes with an uneven number of homologous chromosomes, making sexual reproduction unlikely.
What happens in meiosis I that does not occur in meiosis II?
Meiosis is the production of four genetically diverse haploid daughter cells from one diploid parent cell. … In meiosis II, these chromosomes are further separated into sister chromatids. Meiosis I includes crossing over or recombination of genetic material between chromosome pairs, while meiosis II does not.
Is nondisjunction more common in meiosis I or II?
Among the 188 maternal cases, nondisjunction occurred in meiosis I in 128 cases and in meiosis II in 38 cases; in 22 cases the DNA markers used were uninformative. Therefore meiosis I was responsible for 77.1% and meiosis II for 22.9% of maternal nondisjunction.
What happens if nondisjunction occurs in meiosis 1?
During anaphase, sister chromatids (or homologous chromosomes for meiosis I), will separate and move to opposite poles of the cell, pulled by microtubules. In nondisjunction, the separation fails to occur causing both sister chromatids or homologous chromosomes to be pulled to one pole of the cell.
What might happen if nondisjunction occurs during meiosis?
If nondisjunction occurs in meiosis I, all four products of meiosis will be chromosomally abnormal. Two of the four products of meiosis will have two copies of the chromosome involved in the nondisjunction event, and two of the four products of meiosis will have no copies of that particular chromosome.